MFG Mizuho Financial Group Inc

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-266555

The Information in this preliminary prospectus supplement and the accompanying prospectus is incomplete and subject to completion and amendment. This preliminary prospectus supplement and the accompanying prospectus is not an offer to sell, nor does it seek an offer to buy, these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED JUNE 29, 2023

PRELIMINARY PROSPECTUS SUPPLEMENT

(To prospectus dated August 5, 2022)

Mizuho Financial Group, Inc.

U.S.$                 % Senior Callable Fixed-to-Fixed Reset Rate Notes due 2029

U.S.$                 % Senior Callable Fixed-to-Fixed Reset Rate Notes due 2034

Mizuho Financial Group, Inc., a joint stock corporation incorporated with limited liability under the laws of Japan (“Mizuho Financial Group” or the “Issuer”), will issue an aggregate principal amount of $             of senior callable fixed-to-fixed reset rate notes due July     , 2029 (the “6-year Notes”) and an aggregate principal amount of $             of senior callable fixed-to-fixed reset rate notes due July     , 2034 (the “11-year Notes” and, together with the 6-year Notes, the “Notes,” or the “Fixed-to-Fixed Reset Rate Notes”).

The 6-year Notes will bear interest (i) from (and including) July     , 2023 to (but excluding) July     , 2028 (the “6-year Notes Reset Date”), at the fixed rate of         % per annum, payable semi-annually in arrears on January      and July      of each year, with the first interest payment to be made on January     , 2024, and (ii) from (and including) the 6-year Notes Reset Date to (but excluding) the maturity date, at a fixed per annum rate equal to the applicable U.S. Treasury Rate (as defined below) as determined by the Calculation Agent (as defined below) on the 6-year Notes Reset Determination Date (as defined below) as described under “Description of the Notes—Fixed-to-Fixed Reset Rate Notes—Determination of the U.S. Treasury Rate,” plus         %, payable semi-annually in arrears on January     , 2029 and July     , 2029. The 6-year Notes will mature on July     , 2029.

The 11-year Notes will bear interest (i) from (and including) July     , 2023 to (but excluding) July     , 2033 (the “11-year Notes Reset Date”), at the fixed rate of                % per annum, payable semi-annually in arrears on January      and July      of each year, with the first interest payment to be made on January     , 2024, and (ii) from (and including) the 11-year Notes Reset Date to (but excluding) the maturity date, at a fixed per annum rate equal to the applicable U.S. Treasury Rate as determined by the Calculation Agent on the 11-year Notes Reset Determination Date (as defined below) as described under “Description of the Notes—Fixed-to-Fixed Reset Rate Notes—Determination of the U.S. Treasury Rate,” plus         %, payable semi-annually in arrears on January     , 2034 and July     , 2034. The 11-year Notes will mature on July     , 2034.

Mizuho Financial Group may redeem, at its option, each series of the Notes, in whole, but not in part, on the date that is one year prior to the maturity date of such series of Notes, at the applicable redemption price, subject to certain conditions. See “Description of Notes—Optional Redemption.” In addition, Mizuho Financial Group may at its option redeem the Notes of each series, in whole, but not in part, upon the occurrence of certain changes in Japanese tax law, subject to certain conditions. See “Description of the Notes—Optional Tax Redemption.” Each series of the Notes will not be subject to any sinking fund. The Notes will be represented by one or more global notes deposited with a custodian for and registered in the name of a nominee of The Depository Trust Company (“DTC”), as depositary. Beneficial interests in the Notes will be shown on, and transfers thereof will be effected only through, records maintained by DTC and its direct and indirect participants, including Euroclear Bank SA/NV (“Euroclear”), and Clearstream Banking S.A. (“Clearstream”). The Notes will be issued only in registered form in minimum denominations of $200,000 and integral multiples of $1,000 in excess thereof.

The net proceeds from the issuance and sale of the 6-year Notes will be used to make a loan to Mizuho Bank (as defined below), which intends to utilize an amount equal to the net proceeds to finance and/or refinance, in whole or in part, certain Eligible Green Projects (as defined below). The net proceeds from the issuance and sale of the 11-year Notes will be used to make a loan to Mizuho Bank, which intends to utilize such funds for its general corporate purposes. See “Use of Proceeds.”

Each series of the Notes is intended to qualify as external total loss-absorbing capacity (“TLAC”) debt under the Japanese TLAC Standard (as defined below). The Notes will be Mizuho Financial Group’s direct, unconditional, unsubordinated and unsecured obligations and rank pari passu and without preference among themselves and with all other unsecured obligations, other than subordinated obligations of Mizuho Financial Group (except for statutorily preferred exceptions) from time to time outstanding. See also “Risk Factors—Risks Relating to the Notes—The Notes will be structurally subordinated to the liabilities of our subsidiaries, including Mizuho Bank and Mizuho Trust & Banking.”

We have made an application to the Luxembourg Stock Exchange to list the Notes on the official list of the Luxembourg Stock Exchange and for such Notes to be admitted to trading on the Luxembourg Stock Exchange’s Euro MTF Market. The Luxembourg Stock Exchange’s Euro MTF Market is not a regulated market for the purposes of Directive 2014/65/EU (“MiFID II”) or Regulation (EU) No 600/2014 as it forms part of domestic law in the United Kingdom (as amended, “UK MiFIR”). This prospectus supplement with the accompanying prospectus constitutes the listing prospectus for purposes of Part IV of the Luxembourg law on prospectuses for securities dated July 16, 2019. This prospectus supplement and the accompanying prospectus do not constitute a prospectus for the purposes of Regulation (EU) 2017/1129 or such regulation as it forms part of domestic law in the United Kingdom by virtue of the European Union (Withdrawal) Act 2018 (as amended, the “EUWA”).

Investing in the Notes involves risks. You should carefully consider the risk factors set forth in “Item 3.D. Key Information—Risk Factors” of our most recent annual report on Form 20-F filed with the U.S. Securities and Exchange Commission (the “SEC”), and in the “Risk Factors ” section beginning on page S-8 of this prospectus supplement before making any decision to invest in the Notes.

Neither the SEC nor any state securities commission has approved or disapproved of the Notes or passed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.

The Notes offered by this prospectus supplement and the accompanying prospectus are being offered by the underwriters, subject to prior sale, withdrawal, cancellation or modification of the offer without notice, to delivery to and acceptance by the underwriters and to certain further conditions. It is expected that the Notes will be delivered in book-entry form only, on or about July     , 2023, through the facilities of DTC and its participants, including Euroclear and Clearstream.

Joint Lead Managers and Joint Bookrunners

The date of this prospectus supplement is June     , 2023.

TABLE OF CONTENTS

Prospectus Supplement

Prospectus

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Japan

The Notes have not been and will not be registered under the Financial Instruments and Exchange Act of Japan (Act No. 25 of 1948), as amended, (the “Financial Instruments and Exchange Act”) and are subject to the Special Taxation Measures Act of Japan (Act No. 26 of 1957), as amended (the “Special Taxation Measures Act”). The Notes may not be offered or sold in Japan or to, or for the benefit of, any resident of Japan (which term as used in this sentence means any person resident of Japan, including any corporation or other entity organized under the laws of Japan) or to others for reoffering or resale, directly or indirectly, in Japan or to, or for the benefit of, any resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the Financial Instruments and Exchange Act and any other applicable laws, regulations and governmental guidelines of Japan. See “Underwriting (Conflicts of Interest).” The Notes are not, as part of the distribution by the underwriters pursuant to the underwriting agreement dated the date hereof at any time, to be directly or indirectly offered or sold to, or for the benefit of, any person other than a beneficial owner that is, (i) for Japanese tax purposes, neither (x) an individual resident of Japan or a Japanese corporation, nor (y) an individual non-resident of Japan or a non-Japanese corporation that in either case is a person having a special relationship with Mizuho Financial Group as described in Article 6, Paragraph 4 of the Special Taxation Measures Act (a “specially-related person of Mizuho Financial Group”) or (ii) a Japanese designated financial institution, designated in Article 6, Paragraph 11 of the Special Taxation Measures Act, except as specifically permitted under the Special Taxation Measures Act. BY SUBSCRIBING FOR THE NOTES, AN INVESTOR WILL BE DEEMED TO HAVE REPRESENTED IT IS A PERSON WHO FALLS INTO THE CATEGORY OF (i) OR (ii) ABOVE.

Interest payments on the Notes will generally be subject to Japanese withholding tax unless it is established that such Notes are held by or for the account of a beneficial owner that is (i) for Japanese tax purposes, neither (x) an individual resident of Japan or a Japanese corporation, nor (y) an individual non-resident of Japan or a non-Japanese corporation that in either case is a specially-related person of Mizuho Financial Group, (ii) a Japanese designated financial institution described in Article 6, Paragraph 11 of the Special Taxation Measures Act which complies with the requirement for tax exemption under that paragraph or (iii) a Japanese public corporation, a Japanese financial institution or a Japanese financial instruments business operator described in Article 3-3, Paragraph 6 of the Special Taxation Measures Act which complies with the requirement for tax exemption under that paragraph.

Interest payments on the Notes to an individual resident of Japan, to a Japanese corporation not described in the preceding paragraph, or to an individual non-resident of Japan or a non-Japanese corporation that in either case is a specially-related person of Mizuho Financial Group will be subject to deduction in respect of Japanese income tax at a current rate of 15.315% (15% on or after January 1, 2038) of the amount of such interest.

The European Economic Area

PROHIBITION OF SALES TO EEA RETAIL INVESTORS—The Notes are not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the European Economic Area (the “EEA”). For these purposes, a retail investor means a person who is one (or more) of: (i) a retail client as defined in point (11) of Article 4(1) of Directive 2014/65/EU, or MiFID II as amended; or (ii) a customer within the meaning of Directive 2016/97/EU, as amended, where that customer would not qualify as a professional client as defined in point (10) of Article 4(1) of MiFID II. Consequently, no key information document required by Regulation (EU) No 1286/2014, or the PRIIPs Regulation as amended, for offering or selling the Notes or otherwise making them available to any retail investors in the EEA has been prepared and therefore offering or selling the Notes or otherwise making them available to any retail investor in the EEA may be unlawful under the PRIIPs Regulation.

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United Kingdom

PROHIBITION OF SALES TO UK RETAIL INVESTORS—The Notes are not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the United Kingdom (“UK”). For these purposes, a retail investor means a person who is one (or more) of: (i) a retail client, as defined in point (8) of Article 2 of Regulation (EU) No 2017/565 as it forms part of domestic law by virtue of the European Union (Withdrawal) Act 2018 (as amended, the “EUWA”); or (ii) a customer within the meaning of the provisions of the Financial Services and Markets Act 2000 (“FSMA”) and any rules or regulations made under the FSMA to implement Directive (EU) 2016/97, where that customer would not qualify as a professional client, as defined in point (8) of Article 2(1) of Regulation (EU) No 600/2014 as it forms part of domestic law by virtue of the EUWA. Consequently, no key information document required by Regulation (EU) No 1286/2014 as it forms part of domestic law by virtue of the EUWA (the “UK PRIIPs Regulation”) for offering or selling the Notes or otherwise making them available to retail investors in the UK has been prepared and therefore offering or selling the Notes or otherwise making them available to any retail investor in the UK may be unlawful under the UK PRIIPs Regulation.

There are restrictions on the offer and sale of the Notes in the UK. All applicable provisions of the FSMA with respect to anything done by any person in relation to the Notes in, from, or otherwise involving, the UK must be complied with. See “Underwriting (Conflicts of Interest)—Notice to Prospective Investors in the UK.”

This prospectus supplement is being distributed only to and is directed only at persons located outside the UK or in the UK to (i) persons who have professional experience in matters relating to investments falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the “Financial Promotion Order”); or (ii) high net worth entities falling within Article 49(2)(a) to (d) of the Financial Promotion Order; or (iii) persons to whom it may otherwise lawfully be communicated (all such persons together being referred to as “relevant persons”). This prospectus supplement must not be acted on or relied on in the UK by persons who are not relevant persons. In the UK, any investment or investment activity to which this prospectus supplement relates is only available to, and will be engaged in with, relevant persons.

Singapore

Notification under section 309B of the Securities and Futures Act 2001 of Singapore, as modified or amended from time to time (the “SFA”): The Notes are prescribed capital markets products (as defined in the Securities and Futures (Capital Markets Products) Regulations 2018) and Excluded Investment Products (as defined in MAS Notice SFA 04-N12: Notice on the Sale of Investment Products and MAS Notice FAA-N16: Notice on Recommendations on Investment Products).

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document consists of two parts. The first part is this prospectus supplement, which describes the specific terms of the offering of the Notes and also adds to, updates and changes information contained in the prospectus filed with the SEC dated August 5, 2022, and the documents incorporated by reference in this prospectus supplement. The second part is the above-mentioned prospectus, to which we refer as the “accompanying prospectus.” The accompanying prospectus contains a description of the senior and subordinated debt securities and gives more general information, some of which may not apply to the Notes. If the description of the Notes in this prospectus supplement differs from the description in the accompanying prospectus, the description in this prospectus supplement supersedes the description in the accompanying prospectus.

We have not, and the underwriters have not, authorized any other person to provide you with any information other than that contained in or incorporated by reference into this prospectus supplement, in the accompanying prospectus or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. “Incorporated by reference” means that we can disclose important information to you by referring you to another document filed separately with the SEC. We are not responsible for, and can provide no assurance as to the accuracy of, any other information that any other person may give you. We are not making, nor are the underwriters making, an offer to sell the Notes in any jurisdiction where the offer or sale is not permitted. You should not assume that the information appearing in this prospectus supplement, the accompanying prospectus or in any free writing prospectus prepared by or on behalf of us or to which we have referred you, including any information incorporated by reference herein or therein, is accurate as of any date other than its respective date. Our business, financial condition, results of operations and prospects may have changed since those respective dates.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein contain in a number of places forward-looking statements regarding our intent, belief, targets or current expectations of our management with respect to our financial condition and future results of operations. These statements constitute “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the U.S. Securities Exchange Act of 1934, as amended, or the Exchange Act. In many cases, but not all, we use such words as “aim,” “anticipate,” “believe,” “endeavor,” “estimate,” “expect,” “intend,” “may,” “plan,” “probability,” “project,” “risk,” “seek,” “should,” “strive,” “target” and similar expressions in relation to us or our management to identify forward-looking statements. You can also identify forward-looking statements by discussions of strategy, plans or intentions. These statements reflect our current views with respect to future events and are subject to risks, uncertainties and assumptions. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, our actual results may vary materially from those we currently anticipate.

We have identified some of the risks inherent in forward-looking statements in “Item 3.D. Key Information—Risk Factors” of our most recent annual report on Form 20-F and in the “Risk Factors” section of this prospectus supplement. Other factors could also adversely affect our results or the accuracy of forward-looking statements in this prospectus supplement, the accompanying prospectus or the documents incorporated by reference herein and therein, and you should not consider these to be a complete set of all potential risks or uncertainties.

The forward-looking statements included or incorporated by reference in this prospectus supplement and the accompanying prospectus are made only as of the dates on which such statements were made. We expressly disclaim any obligation or undertaking to release any update or revision to any forward-looking statement contained herein or therein to reflect any change in our expectations with regard thereto or any change in events, conditions or circumstances on which any statement is based.

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PRESENTATION OF FINANCIAL AND OTHER INFORMATION

In this prospectus supplement, the accompanying prospectus and any documents incorporated by reference herein or therein, “MHFG,” “Mizuho Group,” “we,” “us,” and “our” refer to Mizuho Financial Group, Inc. and, unless the context indicates otherwise, its consolidated subsidiaries. “Mizuho Financial Group” refers to Mizuho Financial Group, Inc. Furthermore, unless the context indicates otherwise, these references are intended to refer to us as if we had been in existence in our current form for all periods referred to herein. We use the word “you” to refer to prospective investors in the Notes and the word “Noteholder” or “Noteholders” to refer to the holders of the Notes.

Our primary financial statements for SEC reporting purposes are prepared on an annual and semi-annual basis in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”), while our financial statements for reporting in our jurisdiction of incorporation and Japanese bank regulatory purposes are prepared in accordance with accounting principles generally accepted in Japan (“Japanese GAAP”). Unless otherwise specified, for purposes of this prospectus supplement, we have presented our financial information in accordance with U.S. GAAP. Unless otherwise stated or otherwise required by the context, all amounts in our financial statements are expressed in yen.

There are certain differences between U.S. GAAP and Japanese GAAP. For a description of certain differences between U.S. GAAP and Japanese GAAP, see “Item 5. Operating and Financial Review and Prospects—Reconciliation with Japanese GAAP” in our most recent annual report on Form 20-F filed with the SEC. You should consult your own professional advisers for a more complete understanding of the differences between U.S. GAAP, Japanese GAAP and the generally accepted accounting principles of other countries and how those differences might affect the financial information contained or incorporated by reference in this prospectus supplement or the accompanying prospectus.

Financial information for us contained or incorporated by reference herein or in the accompanying prospectus is presented in accordance with U.S. GAAP or Japanese GAAP, as specified herein or in the relevant document being incorporated by reference. See “Incorporation by Reference” for a list of documents being incorporated by reference herein.

In this prospectus supplement and the accompanying prospectus, references to “U.S. dollars,” “dollars,” “U.S. $” and “$” refer to the lawful currency of the United States, those to “EUR” and “€” refer to the currency of the European Economic and Monetary Union and those to “yen” and “¥” refer to the lawful currency of Japan. This prospectus supplement, the accompanying prospectus or the documents incorporated by reference herein and therein may contain a translation of certain Japanese yen amounts into U.S. dollars for your convenience. However, these translations should not be construed as representations that such yen amounts have been, could have been or could be converted into dollars at the relevant rate or at all.

In this prospectus supplement and the accompanying prospectus, yen figures and percentages presented in accordance with U.S. GAAP have been rounded to the figures shown, and yen figures and percentages presented in accordance with Japanese GAAP have been truncated to the figures shown, except for figures based on managerial accounting, which are rounded, and, in each case, unless otherwise specified. However, in some cases, figures presented in tables have been adjusted to match the sum of the figures with the total amount, and such figures may also be referred to in the related text.

Our fiscal year end is March 31. References to years not specified as being fiscal years are to calendar years.

In this prospectus supplement, all of our financial information is presented on a consolidated basis, unless we state otherwise.

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RISK FACTORS

Investing in the Notes involves risks. You should consider carefully the risks relating to the Notes described below, as well as the other information presented in, or incorporated by reference into, this prospectus supplement and the accompanying prospectus, before you decide whether to invest in the Notes. If any of these risks actually occurs, our business, financial condition and results of operations could suffer, and the trading price and liquidity of the Notes offered could decline, in which case you may lose all or part of your investment. The following does not describe all the risks of an investment in the Notes. Prospective investors should consult their own financial and legal advisers about risks associated with investment in the Notes and the suitability of investing in the Notes in light of their particular circumstances.

This prospectus supplement and the accompanying prospectus also contain forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those anticipated in these forward-looking statements as a result of various factors, including the risks described below, elsewhere in this prospectus supplement and in “Item 3.D. Key Information—Risk Factors” of our annual report on Form 20-F for the fiscal year ended March 31, 2023, which is incorporated herein by reference.

Risks Relating to Our Business

For information on risks relating to our business, see “Item 3.D. Key Information—Risk Factors” in our most recent annual report on Form 20-F, which is incorporated by reference in this prospectus supplement, and similar information in any other documents incorporated by reference herein.

Risks Relating to the Notes

The Notes will be structurally subordinated to the liabilities of our subsidiaries, including Mizuho Bank and Mizuho Trust & Banking.

Your claim as a Noteholder is structurally subordinated to the liabilities of our banking and other subsidiaries, including our subsidiaries’ liabilities for deposits, borrowed money, derivative transactions and trade payables. As a Noteholder, you will only be entitled to assert a claim as a creditor of Mizuho Financial Group that is to be paid out of Mizuho Financial Group’s assets. If any of our subsidiaries becomes subject to insolvency or liquidation proceedings, you will have no right to proceed against such subsidiary’s assets.

Mizuho Financial Group is a holding company that currently has no significant assets other than its investments in, or loans to, its subsidiaries, including Mizuho Bank and Mizuho Trust & Banking. Mizuho Financial Group’s ability to service its debt obligations, including its obligations under the Notes, thus depends on the dividends, loan payments and other funds Mizuho Financial Group receives from its subsidiaries. Mizuho Financial Group may not be able to receive such funds from a subsidiary due to adverse changes in its financial performance or material deterioration in its financial condition, restrictions imposed as a result of such adverse change or deterioration by relevant laws and regulations, including banking and other regulations (such as loss absorption requirements) and limitations under general corporate law, or any contractual obligations applicable to such subsidiary. Furthermore, if a subsidiary becomes subject to insolvency or liquidation proceedings, Mizuho Financial Group’s right to participate in such subsidiary’s assets will be subject to the prior claims of the creditors and any preference shareholders of the subsidiary, except where Mizuho Financial Group is a creditor or preference shareholder with claims that are recognized to be ranked either ahead of or pari passu with such claims. As a result, you may not recover your investment in the Notes in full or at all even though the investors in or creditors of our subsidiaries may recover their investments in full.

Mizuho Financial Group’s loans to, or investments in capital instruments issued by, its subsidiaries made or to be made with the net proceeds from the sale of its instruments may contain contractual mechanisms that, upon the occurrence of a trigger event relating to prudential or financial condition or other events applicable to Mizuho

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Financial Group or its subsidiaries under regulatory requirements, including the Internal TLAC (as defined below) requirements in Japan, will result in a write-down, write-off or conversion into equity of such loans or investments, or other changes in the legal or regulatory form or the ranking of the claims Mizuho Financial Group has against the subsidiaries. For example, to ensure that each of its material subsidiaries in Japan deemed systemically important by the FSA maintains the required minimum level of Internal TLAC under the Internal TLAC requirements in Japan, Mizuho Financial Group may extend to such subsidiaries, using the net proceeds from the sale of the senior debt securities and other debt instruments, subordinated loans that qualify as Internal TLAC instruments pursuant to the Internal TLAC requirements in Japan, including those containing contractual loss absorption provisions (“Contractual Loss Absorption Provisions”) that will discharge or extinguish the loans or convert them into ordinary shares of the subsidiaries if the FSA determines that the relevant subsidiaries are non-viable due to material deterioration in their financial condition after recognizing that they are or are likely to be unable to fully perform their obligations with their assets, or that they have suspended, or are likely to suspend, repayment of their obligations. Any such write-down, write-off or conversion into equity, or changes in the legal or regulatory form or the ranking, or the triggering of Contractual Loss Absorption Provisions, could adversely affect Mizuho Financial Group’s ability to obtain repayment of such loans and investments and to meet its obligations under the Notes as well as the value of the Notes.

The Notes may become subject to loss absorption if Mizuho Financial Group becomes subject to orderly resolution measures under the Deposit Insurance Act of Japan and Japanese insolvency laws. As a result, the value of the Notes could be materially adversely affected, and you may lose all or a portion of your investments.

In November 2015, the Financial Stability Board issued the final TLAC standard for global systemically important banks (“G-SIBs”), including us. The Financial Stability Board’s TLAC standard is designed to ensure that, if a G-SIB fails, it has sufficient loss-absorbing and recapitalization capacity available in resolution to implement an orderly resolution that minimizes the impact on financial stability, thereby ensuring the continuity of critical functions and avoiding exposing public funds to loss. The Financial Stability Board’s TLAC standard defines a minimum requirement for the instruments and liabilities that should be readily available to absorb losses in resolution. For more information regarding the Financial Stability Board’s TLAC standards, see “Item 4.B. Information on the Company—Business Overview—Supervision and Regulation—Japan—Total Loss Absorbing Capacity” in our annual report on Form 20-F for the fiscal year ended March 31, 2023, which is incorporated herein by reference. The FSA published its policy describing its approach for the introduction of this standard in Japan in April 2016, and a revised version of this document was published in April 2018 (the “FSA’s Approach”). In March 2019, the FSA published regulatory notices and related materials to implement the TLAC requirements in Japan. The TLAC standard set forth in these FSA documents (the “Japanese TLAC Standard”), which (i) was phased in from March 31, 2019 and has been fully applied from March 31, 2022 for G-SIBs in Japan, and (ii) has been phased in from March 31, 2021 and will be fully applied from March 31, 2024 for a financial group designated as a domestic systemically important bank in Japan by the FSA which is deemed to be in particular need of a cross-border resolution arrangement and to be of particular systemic significance to the Japanese financial system in the event of its failure (such domestic systemically important bank, together with G-SIBs in Japan, the “Covered SIBs”), and the FSB’s TLAC standard requires Domestic Resolution Entities (as defined below) designated for Covered SIBs to meet certain minimum external TLAC requirements and to cause any of their material subsidiaries in Japan deemed systemically important by the FSA or their foreign subsidiaries subject to TLAC or similar requirements in the relevant jurisdictions to maintain a certain minimum level of capital and debt having internal loss-absorbing and recapitalization capacity (“Internal TLAC”). The FSA designated as resolution entities in Japan (the “Domestic Resolution Entities”) the ultimate holding company in Japan of each Covered SIB. Under the Japanese TLAC Standard, the FSA designated us as the Domestic Resolution Entity for the Mizuho Group, which is subject to the external TLAC requirements in Japan, and also designated Mizuho Bank, Mizuho Trust & Banking and Mizuho Securities as our material subsidiaries in Japan, which are subject to the Internal TLAC requirements in Japan. Under the Japanese TLAC Standard, unsecured senior debt issued by the Domestic Resolution Entity for a Japanese G-SIB is not required to include any contractual write-down, write-off or conversion provisions in order to qualify as external TLAC debt. In addition, unsecured senior debt issued by the Domestic Resolution Entity for a Japanese G-SIB is not required

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to include any subordination provisions in order to qualify as external TLAC debt, so long as its creditors are recognized as structurally subordinated to the creditors of its subsidiaries and affiliates by the FSA on the grounds that the amount of excluded liabilities as defined in the Japanese TLAC Standard of such Domestic Resolution Entity ranking pari passu or junior to its unsecured senior liabilities does not exceed 5% of its external TLAC in principle, while the Internal TLAC incurred by material subsidiaries of a Japanese G-SIB is required to include the Contractual Loss Absorption Provisions and to be subordinated to such entity’s excluded liabilities. The Notes are intended to qualify as external TLAC debt under the Japanese TLAC Standard, due in part to their structural subordination.

The Notes are expected to become subject to loss absorption if Mizuho Financial Group becomes subject to orderly resolution measures under the Deposit Insurance Act and Japanese insolvency laws. The resolution framework for financial institutions under current Japanese laws and regulations includes (i) measures applied to financial institutions that are solvent on a balance sheet basis and (ii) orderly resolution measures applied to financial institutions that have failed or are deemed likely to fail. The framework applies to banks and certain other financial institutions as well as financial holding companies, such as Mizuho Financial Group. In the Japanese TLAC Standard and the FSA’s Approach, the FSA expressed its view that Single Point of Entry (“SPE”) resolution, in which a single national resolution authority applies its resolution tools to the ultimate holding company in Japan of a group, would be the preferred strategy for resolution of Covered SIBs. However, it is uncertain which resolution strategy or specific measures will be taken in a given case, including whether or not the SPE resolution strategy is to be chosen and implemented in a given case, and orderly resolution measures may be applied without implementing any of the measures described in (i) above. Under a possible model of SPE resolution described in the Japanese TLAC Standard, if the FSA determines that a material subsidiary in Japan of a financial institution that is a Japanese G-SIB is non-viable due to a material deterioration in its financial condition after recognizing that it is, or is likely to be, unable to fully perform its obligations with its assets, or that it has suspended, or is likely to suspend, repayment of its obligations, and issues an order concerning restoration of financial soundness, including recapitalization and restoration of liquidity of such material subsidiary, to the Domestic Resolution Entity for the financial institution under Article 52-33, Paragraph 1 of the Banking Act of Japan (Act No. 59 of 1981, as amended), the material subsidiary’s Internal TLAC instruments will be written off or, if applicable, converted into equity in accordance with the applicable Contractual Loss Absorption Provisions of such Internal TLAC instruments. Following the write-off or conversion of Internal TLAC instruments, if the Prime Minister recognizes that the financial institution is or is likely to be unable to fully perform its obligations with its assets, or that it has suspended, or is likely to suspend, repayment of its obligations, as a result of the financial institution’s loans to, or other investment in, its material subsidiaries that are designated by FSA as being systemically important or that are subject to TLAC requirements or similar requirements imposed by a relevant foreign authority, becoming subject to loss absorption or otherwise, and further recognizes that the failure of such financial institution is likely to cause a significant disruption to the Japanese financial market or system, the Prime Minister may, following deliberation by the Financial Crisis Management Meeting, confirm that measures set forth in Article 126-2, Paragraph 1, Item 2 of the Deposit Insurance Act, generally referred to as specified item 2 measures (tokutei dai nigo sochi), need to be applied to the financial institution for its orderly resolution. Any such confirmation by the Prime Minister would also trigger the point of non-viability clauses of Additional Tier 1 and Tier 2 instruments issued by the financial institution, causing such instruments to be written off, or if applicable, converted into equity.

Under current Japanese laws and regulations, upon the application of specified item 2 measures (tokutei dai nigo sochi), a financial institution will be placed under special supervision (tokubetsu kanshi) by, or if the Prime Minister so orders, under special control (tokutei kanri) of, the Deposit Insurance Corporation. In an orderly resolution, if the financial institution is placed under special control (tokutei kanri), pursuant to Article 126-5 of the Deposit Insurance Act, the Deposit Insurance Corporation would control the operation and management of the financial institution’s business, assets and liabilities, including the potential transfer to a bridge financial institution established by the Deposit Insurance Corporation as its subsidiary, or such other financial institution as the Deposit Insurance Corporation may determine, of the financial institution’s systemically important assets and liabilities, which in the case of Mizuho Financial Group would be expected to include the shares of Mizuho

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Bank, Mizuho Trust & Banking, Mizuho Securities and other material subsidiaries based on the Japanese TLAC Standard. Under the Japanese TLAC Standard, to facilitate that transfer, the Prime Minister may prohibit by its designation creditors of the financial institution from attaching any of our assets and claims which are to be transferred to a bridge financial institution or another financial institution pursuant to Article 126-16 of the Deposit Insurance Act. See also “Item 4. B. Information on the Company—Business Overview—Supervision and Regulation—Japan—Governmental Measures to Treat Troubled Institutions” in our annual report on Form 20-F for the fiscal year ended March 31, 2023, which is incorporated herein by reference. In addition, with respect to the Notes, given they are governed by the laws of the State of New York, the terms of the Notes will, in order to satisfy the requirements under the Japanese TLAC Standard, expressly limit the ability of the Noteholders to initiate any action to attach any of our assets, the attachment of which is so prohibited by the Prime Minister under Article 126-16 of the Deposit Insurance Act (or any successor provision thereto) for a period of 30 days from and including the date upon which the Prime Minister confirms that specified item 2 measures (tokutei dai nigo sochi) need to be applied to Mizuho Financial Group. See “Description of the Debt Securities—Limitation on Actions for Attachment” in the accompanying prospectus. The value of assets subject to a prohibition of attachment may decline while such prohibition is in effect, and following such period, Noteholders will be unable to attach any assets that have been transferred to a bridge financial institution or such other financial institution as part of our orderly resolution. The Deposit Insurance Corporation would also control the repayment of liabilities of the financial institution, and, ultimately, facilitate the orderly resolution of the financial institution through court-administrated insolvency proceedings. The Deposit Insurance Corporation has broad discretion in its application of these measures in accordance with the Deposit Insurance Act, Japanese insolvency laws and other relevant laws.

Under current Japanese laws and regulations, if Mizuho Financial Group becomes subject to specified item 2 measures (tokutei dai nigo sochi), the application of specified item 2 measures (tokutei dai nigo sochi) or other measures by, or any decision of, the Prime Minister, the Deposit Insurance Corporation or a Japanese court may result in your rights as a Noteholder or the value of your investment in the Notes being adversely affected. Under the Japanese TLAC Standard, it is currently expected that the Notes will not be transferred to a bridge financial institution or other transferee in the orderly resolution process but will remain as Mizuho Financial Group’s liabilities subject to court-administered insolvency proceedings. On the other hand, in an orderly resolution process, the shares of Mizuho Financial Group’s material subsidiaries may be transferred to a bridge financial institution or other transferee, pursuant to the authority of the Deposit Insurance Corporation to represent and manage and dispose of Mizuho Financial Group’s assets under Article 126-5 of the Deposit Insurance Act, with the permission of a Japanese court in accordance with Article 126-13 of the Deposit Insurance Act, which permission may be granted by court in accordance with the Deposit Insurance Act if (i) the financial institution is under special supervision (tokubetsu kanshi) by, or under special control (tokutei kanri) of, the Deposit Insurance Corporation pursuant to the Deposit Insurance Act, and (ii) the financial institution is, or is likely to be, unable to fully perform its obligations with its assets, or the financial institution has suspended, or is likely to suspend, repayment of its obligations, and Mizuho Financial Group would only be entitled to receive consideration representing the fair values of such shares, which could be significantly less than the book values of such shares. With respect to such transfer, given the Notes are governed by the laws of the State of New York, in order to satisfy the requirements under the Japanese TLAC Standard, Noteholders expressly acknowledge, accept, consent and agree to any transfer of our assets (including shares of our subsidiaries) or liabilities, or any portions thereof, with the permission of a Japanese court in accordance with Article 126-13 of the Deposit Insurance Act (or any successor provision thereto), including any such transfer made pursuant to the authority of the Deposit Insurance Corporation to represent and manage and dispose of Mizuho Financial Group’s assets under Article 126-5 of the Deposit Insurance Act (or any successor provision thereto). See “Description of the Debt Securities—Permitted Transfer of Assets or Liabilities” in the accompanying prospectus. Following such transfer, the recoverable value of Mizuho Financial Group’s residual assets in court-administered insolvency proceedings may not be sufficient to fully satisfy any payment obligations that Mizuho Financial Group may have under its liabilities, including the Notes. Moreover, the Notes will not be insured or guaranteed by the Deposit Insurance Corporation or any other government agency or insurer. Accordingly, the Noteholders may lose all or a portion of their investments in the Notes in court-administered insolvency proceedings.

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The circumstances surrounding or triggering orderly resolution are unpredictable, and the Japanese TLAC Standard is subject to change.

The application of orderly resolution under the Deposit Insurance Act is inherently unpredictable and depends on a number of factors that may be beyond Mizuho Financial Group’s control. The commencement of the orderly resolution process under the Deposit Insurance Act depends on, among other things, a determination by the Prime Minister, following deliberation by the Financial Crisis Management Meeting, regarding Mizuho Financial Group’s viability, or the viability of one or more of Mizuho Financial Group’s subsidiaries, and the risk that their failures may cause a significant disruption to the financial market or systems in Japan. Under the Japanese TLAC Standard, it is possible that specified item 2 measures (tokutei dai nigo sochi) may be applied to us as a result of, among other things, absorption of losses by us on our loans to or investments in, or any other Internal TLAC of, any of our material subsidiaries or material sub-groups in Japan that are designated as systemically important by the FSA or any of our foreign subsidiaries that are subject to TLAC requirements or similar requirements imposed by a relevant foreign authority, prior to the failure of such subsidiary, pursuant to the terms of such loans, investments or other Internal TLAC or in accordance with applicable Japanese or foreign laws or regulations then in effect. However, under the Japanese TLAC Standard, the actual measures to be taken will be determined by the relevant authorities on a case-by-case basis, and, as a result, it may be difficult to predict when, if at all, Mizuho Financial Group may become subject to an orderly resolution process. Accordingly, the market value of the Notes may not necessarily be evaluated in a manner similar to other types of notes issued by non-financial institutions or by financial institutions subject to different regulatory regimes. For example, any indication that Mizuho Financial Group is approaching circumstances that could result in Mizuho Financial Group becoming subject to an orderly resolution process could also have an adverse effect on the market price and liquidity of the Notes.

In addition, there has been no application of the orderly resolution measures under the Deposit Insurance Act described in this prospectus supplement to date. Such measures are untested and will be subject to interpretation and application by the relevant authorities in Japan. It is uncertain how and under what standards the relevant authorities would determine that Mizuho Financial Group is, or is deemed likely to be unable to fully perform its obligations with its assets, or that Mizuho Financial Group has suspended, or is deemed likely to suspend, repayment of its obligations in determining whether to commence an orderly resolution process, and it is possible that particular circumstances that seem similar may lead to different results. In addition, the sequence and specific actions that will be taken in connection with orderly resolution measures and their impact on the Notes are uncertain. It is also uncertain whether a sufficient amount of assets will ultimately be available to the Noteholders. Mizuho Financial Group’s creditors, including the Noteholders, may encounter difficulty in challenging the application of orderly resolution measures to Mizuho Financial Group.

Although Mizuho Financial Group expects the Notes to qualify as external TLAC due in part to their structural subordination, there is no assurance that the Notes will qualify as such, which could affect our ability to meet the minimum TLAC requirements and subject us to potential adverse regulatory action. The Japanese TLAC Standard requires each Japanese G-SIB to hold external TLAC eligible instruments in an amount not less than 18% of its risk-weighted assets and 6.75% of the applicable Basel III leverage ratio denominator from March 31, 2022, and 7.10% of the applicable Basel III leverage ratio denominator from April 1, 2024, while excluding the amounts of deposits at the Bank of Japan from the total exposure for the purpose of calculation of the applicable Basel III leverage ratio denominator, taking into account exceptional macroeconomic conditions and other circumstances. Under the Japanese TLAC Standard, Japanese G-SIB’s access to Japan’s deposit insurance fund reserves qualifies as TLAC in the amount equivalent to 3.5% of consolidated risk-weighted assets from March 31, 2022. As the Japanese TLAC Standard is subject to change, if such changes occur in the future, may result in us issuing debt instruments in the future with term that differ from those of the Notes, which in turn could adversely affect the value of the Notes.

The Notes are unsecured obligations.

The Notes are unsecured obligations, and their repayment may be compromised if:

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If any of these events occurs, our assets may not be sufficient to pay amounts due on the Notes.

The Indenture and the Notes contain very limited restrictive covenants and provide limited protection in the event of a change in control.

The Indenture in respect of the Notes and the Notes do not contain any financial covenants or other restrictions on our ability to pledge or dispose of assets or to secure other indebtedness, pay dividends on our shares of common stock, incur indebtedness or our ability to issue new securities or repurchase our outstanding securities. These or other actions by us could adversely affect the ability of Mizuho Financial Group to pay amounts due on the Notes. In addition, the Indenture and the Notes do not contain any covenants or other provisions that afford more than limited protection to Noteholders in the event of a change in control. See “Description of the Debt Securities—Covenants” in the accompanying prospectus.

There is no prior market for the Notes, and the Notes may have limited liquidity.

There is no existing market for the Notes. Although we have made an application to the Luxembourg Stock Exchange to list the Notes on the official list of the Luxembourg Stock Exchange and for such Notes to be admitted to trading on the Luxembourg Stock Exchange’s Euro MTF Market, there can be no assurance that any active trading market for the Notes will develop or be sustained or whether, or at what price, Noteholders will be able to sell or otherwise transfer their Notes. The liquidity of any trading market for the Notes will depend upon the number of Noteholders, our results of operations and financial condition, the market for similar securities, the interest of securities dealers in making a market in the Notes and other factors. Although certain underwriters have informed us that they intend to make a market in the Notes, such underwriters are not obligated to do so, and any such market-making activity will be subject to the limits imposed by applicable law and may be interrupted or discontinued at any time without notice. If an active trading market for the Notes does not develop or is not sustained, the market price and liquidity of the Notes may be adversely affected and you may be unable to resell our Notes or may only be able to sell them at a substantial discount.

The ratings on the Notes could be lowered, suspended or withdrawn, and Mizuho Financial Group’s credit ratings may not reflect all risks of an investment in the Notes.

We intend to apply for credit ratings for the Notes. Mizuho Financial Group’s credit ratings may not reflect the potential impact of all risks relating to the market value of the Notes. However, real or anticipated changes in Mizuho Financial Group’s credit ratings will generally affect the market value of the Notes.

In addition, other rating agencies may assign credit ratings to the Notes with or without any solicitation from us and without any provision of information from us. A rating is not a recommendation to buy, sell or hold securities and may be subject to revision, suspension or withdrawal, the assignment of new ratings that are lower than existing ratings, or a downgrade or potential downgrade in the ratings assigned to us, our subsidiaries or any of our respective securities and could reduce the scope of potential investors in the Notes and adversely affect the price and liquidity of the Notes. We have no obligation to inform Noteholders of any such downgrade, suspension, withdrawal or revision.

We may redeem the Notes at our option, subject to certain conditions.

We have the option to redeem each series of the Notes in whole, but not in part, on the date that is one year prior to the maturity date of such series of Notes at 100% of their principal amount plus any accrued and unpaid

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interest to (but excluding) the date of redemption as described under “Description of the Notes—Optional Redemption,” in addition to the option to redeem the Notes of each series in whole, but not in part, at 100% of their principal amount plus any accrued and unpaid interest to (but excluding) the date of redemption upon the occurrence of certain tax events as described under “Description of the Notes—Optional Tax Redemption.” Any such redemption is subject to certain conditions, including our obtaining prior confirmation of the FSA (if and to the extent required under the then applicable Japanese banking laws or regulations), regardless of whether such redemption would be favorable or unfavorable to you.

Any decision by us as to whether we will exercise our option to redeem the Notes will be made at our absolute discretion, subject to certain conditions. Our decision may be influenced by factors such as, but not limited to, the economic impact of exercising such option to redeem the Notes, any tax consequences, the applicable TLAC and other regulatory requirements and the prevailing market conditions. We may, for example, decide to redeem the Notes prior to their maturity date if the interest payable on the Notes is greater than the interest that would be payable on our other outstanding financial instruments of a comparable maturity, of comparable terms and of a comparable credit rating.

You will not have the right to request the redemption of the Notes. As a result, you may be required to bear the financial risks of an investment in the Notes until maturity. You should not invest in the Notes with the expectation that we will exercise our option to redeem the Notes. In addition, our optional redemption of the Notes or the perception that the Notes may be redeemed in the circumstances described above may negatively affect the market value of the Notes. Moreover, if we redeem the Notes, you may not be able to reinvest the redemption proceeds in financial instruments offering a yield comparable to that on the Notes.

Risks Relating to the Fixed-to-Fixed Reset Rate Notes

The interest rate on the Notes will reset on the 6-year Notes Reset Date and the 11-year Notes Reset Date, as applicable.

The interest rate on the Notes will initially be the applicable fixed per annum rate set forth on the cover page of this prospectus supplement from and including the issue date to, but excluding, the 6-year Notes Reset Date and the 11-year Notes Reset Date, as applicable. From and including the 6-year Notes Reset Date and the 11-year Notes Reset Date, as applicable, to, but excluding, the applicable maturity date, the interest rate on the Notes will be reset to a fixed per annum rate equal to the applicable U.S. Treasury Rate as determined by the Calculation Agent on the 6-year Notes Reset Determination Date and the 11-year Notes Reset Determination Date, as applicable, as described under “Description of the Notes—Fixed-to-Fixed Reset Rate Notes—Determination of the U.S. Treasury Rate,” plus the applicable spread set forth on the cover page of this prospectus supplement. As a result, the interest rate on the Notes following the 6-year Notes Reset Date and the 11-year Notes Reset Date, as applicable, may be less than the applicable initial interest rate, which would affect the amount of any interest payments under the Notes and, by extension, could affect their market value.

The historical U.S. Treasury Rates are not an indication of future U.S. Treasury Rates.

The interest rate on the Notes from and including the 6-year Notes Reset Date and the 11-year Notes Reset Date, as applicable, to, but excluding, the applicable maturity date will be reset to a fixed per annum rate to be determined based on the applicable U.S. Treasury Rate on the 6-year Notes Reset Determination Date and the 11-year Notes Reset Determination Date, as applicable. In the past, U.S. Treasury Rates have experienced significant fluctuations. You should note that historical levels, fluctuations and trends of U.S. Treasury Rates are not necessarily indicative of future levels. Any historical upward or downward trend in U.S. Treasury Rates is not an indication that U.S. Treasury Rates are more or less likely to increase or decrease at any time, and you should not take the historical U.S. Treasury Rates as an indication of future rates. You bear the financial risks of fluctuations in the U.S. Treasury Rates and their effect on the interest on, and the market value of, the Notes.

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Risks Relating to the 6-year Notes

The 6-year Notes may not be a suitable investment for all investors seeking exposure to green assets.

Through Mizuho Bank, we intend to use an amount equal to the net proceeds from the offering of the 6-year Notes to finance and/or refinance, in whole or in part, existing and/or new “Eligible Green Projects” as defined under the Green Bond Framework adopted by us. See “Use of Proceeds—Use of Proceeds for the 6-year Notes.” Prospective investors should consider the information set out in this prospectus supplement regarding such use of proceeds and must determine for themselves the relevance of such information for the purpose of any investment in the 6-year Notes together with any other investigation such investor deems necessary. We have significant flexibility in allocating an amount equal to the net proceeds from the 6-year Notes, including reallocating the amount in the event we determine in our discretion that projects receiving allocation no longer meet the criteria for Eligible Green Projects. There can be no assurance that such use of proceeds for any Eligible Green Projects will satisfy, whether in whole or in part, any present or future investor expectations or requirements, taxonomies or standards or other investment criteria or guidelines with which such investor or its investments are required to comply, whether by any present or future applicable law or regulations or by its own bylaws or other governing rules or investment portfolio mandates, ratings criteria, taxonomies or standards or other independent expectations, in particular, with regard to any direct or indirect environmental, sustainability or social impact of any Eligible Green Projects. Furthermore, in connection with the allocation of an amount equal to the net proceeds of the sale of the 6-year Notes to Eligible Green Projects, no assurance can be given that such allocation will be capable of being implemented in such manner or in accordance with any timing schedule, or that any such financing of Eligible Green Projects will be completed within any specified period or at all or with the results or outcome as we originally expected or anticipated.

Any failure to apply an amount equal to the net proceeds from the offering of the 6-year Notes in the manner set out in “Use of Proceeds—Use of Proceeds for the 6-year Notes,” or the withdrawal of any opinion, certification or evaluation of a third party, or any attestation that we are not complying in whole or in part with any matters subject to such opinion, certification or evaluation, or any failure of use of proceeds for any Eligible Green Projects to satisfy investor expectations or requirements, taxonomies or standards or other investment criteria or guidelines, may have a material adverse effect on the value of the 6-year Notes and/or result in adverse consequences for certain investors with portfolio mandates to invest in securities to be used for a particular purpose. However, there is no contractual obligation to allocate an amount equal to the net proceeds of the sale of the 6-year Notes to Eligible Green Projects or to manage and provide periodic progress reports on allocation of such amount or periodic reports on the impact of the Eligible Green Projects as described under “Use of Proceeds—Green Bond Framework—Reporting,” and any failure to do so will not constitute a default or an event of default under the 6-year Notes or the Indenture. We may also in our own discretion update or amend our Green Bond Framework from time to time, including in response to further advances and developments in the Green Bond Principles by the International Capital Market Association, or other applicable industry or government guidelines establishing best practices for the green bond market.

There is no legal, regulatory, or market definition of or standardized criteria for what constitutes a “green,” “social,” “sustainable,” or other equivalently labeled project, and any such designations made by third parties with respect to the 6-year Notes may not be suitable for the investment criteria of an investor.

There is currently no clearly defined definition (legal, regulatory or otherwise) of, nor market consensus as to what constitutes, a “green,” “social,” “sustainable” or an equivalently labeled project, or as to what precise attributes are required for a particular project to be defined as “green,” “social,” “sustainable” or such other equivalent label, and nor can any assurance be given that such a clear definition or consensus will develop over time. Accordingly, no assurance is or can be given to investors that any Eligible Green Projects selected to receive an allocation of funds from the net proceeds of the 6-year Notes will meet any or all investor expectations regarding such “green,” “social,” “sustainable” or other equivalently-labeled performance objectives, or that any adverse environmental, social and/or other impacts will not occur during the implementation of any Eligible Green Projects funded in whole or in part by the funds from the net proceeds of the 6-year Notes. In addition, any

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Eligible Green Projects may become controversial or criticized by activist groups or other stakeholders, which could adversely affect the return on, value of and market for the 6-year Notes.

A framework overview and second-party opinion from Sustainalytics, an outside consultant, regarding our Green Bond Framework has been made publicly available on our website. Furthermore, in connection with the 6-year Notes, we will engage an outside consultant to perform periodic evaluations of the allocation of funds from the 6-year Notes that will contain an assessment as to whether the projects are in line with our Green Bond Framework. Such evaluations will also be made publicly available on our website. No assurance or representation is given as to the suitability or reliability for any purpose whatsoever of any opinion, certification or evaluation of any third party (whether or not solicited by us or Mizuho Bank) that will be made available in connection with the issuance of the 6-year Notes, in particular, as it regards the ability of an Eligible Green Project to fulfill any environmental, social, sustainability or other criteria. No such opinion, certification or evaluation is, nor should it be deemed to be, a recommendation by us, Mizuho Bank, any underwriter with respect to the 6-year Notes or any other person to buy, sell or hold the 6-year Notes. Any such opinion, certification or evaluation is only current as of the date it was initially issued, and withdrawal of any such opinion, certification or evaluation, or the issuance of any additional opinion, certification or evaluation attesting that we are not complying, in whole or in part, with any matters for which such opinion, certification or evaluation is opining or certifying may have a material adverse effect on the value of the 6-year Notes and/or result in adverse consequences for certain investors with mandates to invest in securities to be used for a particular purpose. Prospective investors must determine for themselves the relevance of any such opinion, certification or evaluation and/or the information contained therein and/or the provider thereof for the purpose of any investment in the 6-year Notes. To our knowledge, the providers of such opinions and certifications are not currently subject to any specific regulatory or other regime or oversight. In addition, any such provider will have received fees from us in connection with the issuance of any such opinion or certification. For the avoidance of doubt, no such opinion, certification or evaluation is, nor shall it be deemed to be, incorporated into this prospectus supplement, the accompanying prospectus or any other filing with the SEC.

Furthermore, in the event that the 6-year Notes are listed or admitted to trading on any dedicated “green,” “environmental,” “social,” “sustainable” or other equivalently-labelled segment of any stock exchange or securities market (whether or not regulated), no representation or assurance is given by us or any underwriter or any other person that such listing or admission satisfies, whether in whole or in part, any present or future investor expectations or requirements as regards any investment criteria or guidelines with which such investor or its investments are required to comply, whether by any present or future applicable law or regulations or by its own by-laws or other governing rules or investment portfolio mandates, in particular, with regard to any direct or indirect environmental, social or sustainability impact of any projects or uses, the subject of or related to, any Eligible Green Projects. Furthermore, it should be noted that the criteria for any such listings or admission to trading may vary from one stock exchange or securities market to another. Nor is any representation or assurance given or made by us or any underwriter or any other person that any such listing or admission to trading will be obtained in respect of any such 6-year Notes or, if obtained, that any such listing or admission to trading will be maintained during the life of the 6-year Notes.

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USE OF PROCEEDS

Use of Proceeds for the 6-year Notes

We estimate that we will receive net proceeds from the issuance and sale of the 6-year Notes (after deducting underwriting discounts and estimated offering expenses payable by us) of approximately $             million which we intend to use to make a loan that is intended to qualify as internal TLAC under the Japanese TLAC Standard to Mizuho Bank. Mizuho Bank intends to utilize an amount equal to the net proceeds of the 6-year Notes to finance and/or refinance, in whole or in part, existing and/or new “Eligible Green Projects” as defined under the Green Bond Framework adopted by us. Please see below for a description of our Green Bond Framework and the criteria for Eligible Green Projects. For purposes of these criteria for Eligible Green Projects, the 6-year Notes fall under “Green Bonds.”

Green Bond Framework

The Green Bond Framework is part of our initiative to achieve sustainable and stable growth through which we contribute to the stable development and prosperity of the economy, the industries and the society around the world, and we have identified environmental considerations as one of the key sustainability areas. The Green Bond Framework is not incorporated by reference into this prospectus supplement.

Eligible Green Projects

Under the Green Bond Framework, an “Eligible Green Project” means a project which:

The relevant Project Categories are:

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For clarification purposes, the following are excluded from the Green Bond Framework: fossil fuel-based assets, fossil fuel-based transportation/infrastructure and transportation with the main objective of transporting

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fossil fuel, defense and security, palm oil, wood pulp, nuclear power generation, coal-fired power generation as well as all mining and tobacco sectors.

Process for Project Evaluation and Selection

Eligible Green Projects are evaluated and selected based on compliance with the eligibility criteria above. Eligible Green Projects are identified and selected via a process that involves participants from various functional areas including Mizuho Bank’s Real Estate Finance Department, Project Finance Department and Sustainable Products Promotion Department as well as MHFG’s Corporate & Investment Banking Coordination Department, Global Markets Coordination Department and Financial Planning Department.

Process to Mitigate Environmental and Social Risk

Mizuho Group leverages its financial intermediary and consulting capabilities in order to proactively develop and offer financial products and services which support the environmental initiatives of corporations and other clients. In doing so, we aim to maximize positive impacts and avoid or mitigate negative impacts on the environment. We make decisions on financing and investments after examining the recognized risks based on our Environmental and Social Management Policy for Financing and Investment Activity, and with clients, we discuss or engage in medium- to long-term environmental and social issues. We will revise our policy as needed.

For all project finance related business, Mizuho Bank’s Project Finance Department or other relevant departments evaluate financial viability of projects in accordance with internal credit evaluation process. For any large-scale development projects which have the potential to impact the natural environment and local communities, the Sustainable Development Office of Mizuho Bank’s Sustainable Products Promotion Department (“Sustainable Development Office”) reviews projects and conducts the required due diligence in light of the Equator Principles, and categorizes projects as Category A, B or C⁽¹⁾ based on its internal environmental and social risk assessment process. Such categorization is based on the environmental and social categorization process of the International Finance Corporation, complying with the Equator Principles. As a part of this process, Mizuho Bank evaluates a project for minimal, limited or significant potential adverse environmental and social impact. For each project where limited or significant risk is identified, Mizuho Bank’s internal process requires the Sustainable Development Office to work in partnership with its clients to assess and manage these environmental and social risks and impacts in order to ensure that a project is implemented with full consideration of its impact on the natural environment and local communities.

For Project Category (d), each project is required to be certified to a certain level such as by “LEED,” “BREEAM,” “CASBEE,” “DBJ Green Building Certification” or “BELS,” or aligned with CBI criteria.

Note:

Selection of Eligible Green Projects

As for the selection process of Eligible Green Projects, based on the list of finances offered by Mizuho Bank, MHFG’s Corporate & Investment Banking Coordination Department and others draft the list of Eligible Green Projects. Candidate projects that are suited to any of Project Categories (a) to (h) above, and those that meet condition (ii) above will be proposed by MHFG’s Corporate & Investment Banking Coordination Department and others. Finally, MHFG’s Global Markets Coordination Department and Financial Planning Department will select Eligible Green Projects from the candidate projects list.

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Management of Proceeds

An amount equal to the net proceeds from the sale of a specific issue of Green Bonds will be loaned to Mizuho Bank and allocated by Mizuho Bank to the financing and/or refinancing of existing and/or new Eligible Green Projects. So long as such Green Bonds remain outstanding, MHFG will keep the list of all loans that financed Eligible Green Project based on Mizuho Bank’s internal loan data system and its output, and such records of that list will show an amount equal to the net proceeds from the issuance of such bonds as allocated to the loans that meet MHFG’s internal investment criteria for Eligible Green Projects. Pending the allocation of an amount equal to the net proceeds of such bonds to finance Eligible Green Projects, the unallocated balance will be invested in overnight or otherwise short-term financial instruments and will be allocated to Eligible Green Projects as soon as practicably possible.

Payment of principal of and interest on any Green Bonds will be made from MHFG’s general funds and will not be directly linked to the performance of any Eligible Green Projects.

So long as any Green Bonds are outstanding, MHFG will review and update the list of the Eligible Green Projects to which an amount equal to the net proceeds of the Green Bonds are allocated on an annual basis. Any proceeds allocated to projects that have been sold, prepaid, amortized or otherwise become ineligible shall be reallocated to other Eligible Green Projects.

Reporting

Allocation Reporting

So long as any Green Bonds are outstanding, we will provide and keep readily available, on a designated website, information on the allocation of an amount equal to the net proceeds of the relevant Green Bonds, to be updated at least annually until full allocation and as necessary in each year thereafter in the event of new material developments. This information will include:

An independent party will provide an annual review on the allocation of the use of proceeds as well as impact reporting to verify that allocation and reporting is aligned with the Green Bond Framework.

Environmental Impact Reporting

We intend to report, on a best efforts basis, on the impact of the Eligible Green Projects, to be updated at least annually until full allocation and as necessary in each year thereafter in the event of new developments. All impact reporting (as and when feasible and available) will be disclosed on an aggregate basis by eligible Project Category.

The following sets forth exemplary metrics that we intend to report on a best effort basis for respective Eligible Green Projects:

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For the avoidance of doubt, none of the reports or reviews discussed above are incorporated by reference into this prospectus supplement, the accompanying prospectus or any other filing with the SEC.

The Green Bond Framework adopted by us, pursuant to which the 6-year Notes are being issued, may be updated or amended in our own discretion from time to time, including in response to further advances and developments in the Green Bond Principles by the International Capital Market Association or the Green Bond Guidelines established by the Ministry of the Environment of Japan, or other applicable industry or government guidelines establishing best practices for the green bond market.

Use of Proceeds for the 11-year Notes

We estimate that we will receive net proceeds from the issuance and sale of the 11-year Notes (after deducting underwriting discounts and estimated offering expenses payable by us) of approximately $             million which we intend to use to make a loan that is intended to qualify as Internal TLAC under the Japanese TLAC Standard to Mizuho Bank. Mizuho Bank intends to utilize such funds for its general corporate purposes.

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CAPITALIZATION AND INDEBTEDNESS

The following table sets forth our consolidated capitalization and indebtedness as of March 31, 2023 presented in accordance with U.S. GAAP, as adjusted to give effect to the offering of the Notes. You should read this table in conjunction with the consolidated financial statements and related notes incorporated by reference in this prospectus supplement.

Notes:

Except as stated above, there has been no material change in our capitalization and indebtedness since March 31, 2023.

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SELECTED FINANCIAL AND OTHER INFORMATION (U.S. GAAP)

The following table sets forth our selected consolidated financial data under U.S. GAAP as of and for the fiscal years ended March 31, 2019, 2020, 2021, 2022 and 2023, which have been derived from our audited consolidated financial statements as of and for the same periods.

The consolidated financial statements of Mizuho Financial Group included in our annual report on Form 20-F for the fiscal year ended March 31, 2023 and incorporated herein by reference have been audited in accordance with the standards of the Public Company Accounting Oversight Board (United States) by Ernst & Young ShinNihon LLC, our independent registered public accounting firm.

You should read the U.S. GAAP selected consolidated financial information presented below together with the information included in “Item 5. Operating and Financial Review and Prospects” and the audited consolidated financial statements, including the notes thereto, in our annual report on Form 20-F for the fiscal year ended March 31, 2023, which is incorporated herein by reference. The information presented below is qualified in its entirety by reference to that information.

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Notes:

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SUPPLEMENTAL FINANCIAL AND OTHER INFORMATION (JAPANESE GAAP)

The table below sets forth our selected historical consolidated and other financial data under Japanese GAAP, as of and for the fiscal years ended March 31, 2019, 2020, 2021, 2022 and 2023.

The selected consolidated financial information as of and for the fiscal years ended March 31, 2019, 2020, 2021, 2022 and 2023 has been derived from our audited consolidated financial statements under Japanese GAAP which have been audited by Ernst & Young ShinNihon LLC, our independent auditor, and which are not included in or incorporated by reference into this prospectus supplement.

Some statistical information is primarily reported by Japanese banks on a non-consolidated basis and is presented as such in this prospectus supplement. Selected aggregated non-consolidated figures for the principal banking subsidiaries of the Mizuho Group are also provided for reference purposes.

Japanese GAAP differs in certain respects from U.S. GAAP. For a description of certain differences between U.S. GAAP and Japanese GAAP, see “Item 5. Operating and Financial Review and Prospects—Reconciliation with Japanese GAAP” in our most recent annual report on Form 20-F filed with the SEC, which is incorporated by reference herein.

Selected Consolidated Financial Data for Mizuho Group

The table below sets forth selected historical consolidated financial data, as of and for the fiscal years ended March 31, 2019, 2020, 2021, 2022 and 2023.

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Notes:

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Other Related Information for Mizuho Group

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