Exhibit 5.1

April 17, 2024

Mitsubishi UFJ Financial Group, Inc.

7-1, Marunouchi 2-chome

Chiyoda-ku, Tokyo 100-8330

Japan

MITSUBISHI UFJ FINANCIAL GROUP, INC.

$900,000,000 5.258% Senior Callable Fixed-to-Fixed Reset Rate Notes due April 17, 2030

$1,600,000,000 5.426% Senior Callable Fixed-to-Fixed Reset Rate Notes due April 17, 2035

Ladies and Gentlemen:

In connection with the registration statement (“Registration Statement”) on Form F-3 (File No. 333-273681) relating to senior debt securities of Mitsubishi UFJ Financial Group, Inc. (the “Company”), and the issue and offering outside Japan by the Company of $900,000,000 5.258% Senior Callable Fixed-to-Fixed Reset Rate Notes due April 17, 2030 and $1,600,000,000 5.426% Senior Callable Fixed-to-Fixed Reset Rate Notes due April 17, 2035 (collectively, the “Notes”) pursuant to the underwriting agreement dated April 8, 2024 among the Company and the underwriters named therein (the “Underwriting Agreement”), we have acted as Japanese legal counsel to the Company and have been requested to provide our opinion to be filed as an exhibit to a Current Report on Form 6-K to be filed by the Company on the date hereof incorporated by reference into the Registration Statement.

For the purposes of this opinion, we have examined, inter alia, the following documents:

We have also examined such other certificates and corporate documents of the Company as well as such other matters, documents and records and considered such questions of the laws of Japan, as we have deemed necessary or appropriate for the purpose of rendering the opinion hereinafter set forth.

On the basis of and subject to the foregoing, having regard to the relevant laws of Japan as of the date hereof to the extent that they are applicable, and subject to the assumptions, qualifications and limitations set out herein, we are of the opinion that:

The Notes, when payment for the Notes has been duly made in full in accordance with the Underwriting Agreement, and the Global Certificates have been duly signed on behalf of the Company by a Representative Corporate Executive of the Company or persons named in the Power of Attorney, duly authenticated and delivered in accordance with the terms of the Underwriting Agreement, the Indenture and the Notes, and assuming that the Notes will constitute valid and legally binding obligations of the Company enforceable in accordance with their terms under their governing law, to which they are subject and as to which we render no opinion, will constitute valid and legally binding obligations of the Company enforceable in accordance with their terms.

We have assumed, for the purpose of rendering this opinion, that (i) all signatures or seal impressions on any documents we reviewed are true and genuine; (ii) all documents submitted to us as originals are authentic and complete; (iii) all documents submitted to us as copies are complete and conform to the originals thereof that are authentic and complete; (iv) all documents submitted to us as forms are executed in such forms; (v) statements included, expressly or impliedly, in the documents, record and certificate of the Company or public officials are true and conform to the relevant facts thereof; (vi) all natural person-signatories who have executed or delivered the relevant documents on behalf of the relevant parties thereto have and had at the relevant times sufficient legal capacity to take such actions; (vii) each party (other than the Company) to each of the Underwriting Agreement and the Indenture and other relevant documents is an entity duly organized, validly existing and, where applicable, in good standing under the laws of the jurisdiction of its organization, and has full and complete power and authority (corporate or otherwise) to execute and deliver, and to perform its obligations under, such document; (viii) each of the Underwriting Agreement and the Indenture and other relevant documents is within the capacity in powers of and has been duly authorized by all the parties thereto (other than the Company); (ix) each of the Underwriting Agreement and the Indenture and other relevant documents has been duly executed and delivered by all the parties thereto (other than the Company); (x) nothing in the applicable law of any jurisdiction other than Japan would conflict with, or preclude the performance, legality, effectiveness or enforcement of, the Notes and the Underwriting Agreement, the Indenture and other relevant documents; and (xi) the Underwriting Agreement, the Indenture and other relevant documents are legal, valid and binding on the parties thereto and enforceable in accordance with their respective terms under their respective governing laws (other than the laws of Japan). We have not independently verified any of the matters referred to in (i) to (xi) above.

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The foregoing opinion is based on the assumptions, qualified by and subject to the limitations, set forth below:

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We hereby consent to the use of this opinion as an exhibit to a Current Report on Form 6-K to be filed by the Company on the date hereof incorporated by reference into the Registration Statement and to the use of our name under the captions “Legal Matters” and “Limitations on Enforcement of U.S. Laws” contained in the Registration Statement. In giving this consent, we do not thereby admit that we come within the category of persons whose consent is required by the U.S. Securities Act of 1933, as amended, or by the rules and regulations under it.

(MKK)

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Exhibit 5.2

PAUL, WEISS, RIFKIND, WHARTON & GARRISON LLP

FUKOKU SEIMEI BUILDING, 2-2 UCHISAIWAICHO 2-CHOME,

CHIYODA-KU, TOKYO 100-0011, JAPAN

TELEPHONE (813) 3597-8101

FACSIMILE (813) 3597-8120

April 17, 2024

Mitsubishi UFJ Financial Group, Inc.

7-1, Marunouchi 2-chome

Chiyoda-ku, Tokyo 100-8330

Japan

5.258% Senior Callable Fixed-to-Fixed Reset Rate Notes due 2030

5.426% Senior Callable Fixed-to-Fixed Reset Rate Notes due 2035

Ladies and Gentlemen:

We have acted as U.S. counsel to Mitsubishi UFJ Financial Group, Inc., a joint stock company organized under the laws of Japan (the “Company”), in connection with the Registration Statement on Form F-3ASR (File No. 333-273681) (the “Registration Statement”), which became effective on August 4, 2023. You have asked us to furnish our opinion as to the legality of U.S.$900,000,000 aggregate principal amount of the Company’s 5.258% senior callable fixed-to-fixed reset rate notes due 2030 and U.S.$1,600,000,000 aggregate principal amount of the Company’s 5.426% senior callable fixed-to-fixed reset rate notes due 2035 (collectively, the “Senior Debt Securities”), which are registered under the Registration Statement and which are being sold today pursuant to an Underwriting Agreement, dated April 8, 2024 (the “Underwriting Agreement”), by and among the representatives named therein, as representatives of the underwriters named on Schedule A thereto (the “Underwriters”), and the Company.

The Senior Debt Securities are to be issued under a senior indenture, dated March 1, 2016 (the “Senior Indenture”), by and between the Company, as issuer, and The Bank of New York Mellon, as trustee (the “Trustee”), and pursuant to resolutions adopted by the Company’s Board of Directors.

In connection with the furnishing of this opinion, we have examined originals, or copies certified or otherwise identified to our satisfaction, of the following documents:

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In addition, we have examined such certificates, agreements and documents as we deemed relevant and necessary as a basis for the opinion expressed below. We have also relied as to matters of fact upon oral and written statements of officers and representatives of the Company, the representations and warranties of the Company made in the Underwriting Agreement, and certificates of officers of the Company.

In our examination of the documents referred to above, we have assumed, without independent investigation, the genuineness of all signatures, the legal capacity of all individuals who have executed any of the documents reviewed by us, the authenticity of all documents submitted to us as originals, the conformity to the originals of all documents submitted to us as certified, photostatic, reproduced or conformed copies of valid existing agreements or other documents, the authenticity of the originals of such latter documents, and that the statements regarding matters of fact in the certificates, records, agreements, instruments and documents that we have examined are accurate and complete. We have also assumed, without independent investigation, (i) that the Company is validly existing under the laws of Japan, (ii) that the Company has all necessary corporate power to execute, deliver and perform its obligations under the Underwriting Agreement, the Senior Indenture and the Senior Debt Securities, (iii) that the execution, delivery and performance of the Underwriting Agreement, the Senior Indenture and the Senior Debt Securities by the Company have been duly authorized by all necessary corporate action, and none of the Underwriting Agreement, the Senior Indenture and the Senior Debt Securities violates the Company’s organizational documents, the laws of Japan or the terms of any agreement or instrument to which the Company is subject, and (iv) the authorization, execution and delivery of the Underwriting Agreement, the Senior Indenture and the Senior Debt Securities by the Company under the laws of Japan. We have also assumed that the Senior Indenture has been duly authorized and executed by, and constitutes the legal, valid and binding obligations of, the Trustee, and the due authentication of the Senior Debt Securities by the Trustee in accordance with the Senior Indenture.

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Based upon the foregoing, and subject to the assumptions, exceptions and qualifications set forth in this letter, we are of the opinion that the Senior Debt Securities, when duly executed, issued, delivered and authenticated in accordance with the terms of the Senior Indenture and delivered against the payment as provided in the Underwriting Agreement, will constitute the legal, valid and binding obligations of the Company, enforceable against the Company in accordance with their terms, except that the enforceability of the Senior Debt Securities may be subject to (a) bankruptcy, insolvency, reorganization, fraudulent conveyance or transfer, moratorium and similar laws affecting creditors’ rights generally, and possible judicial action giving effect to governmental actions relating to persons or transactions or foreign laws affecting creditors’ rights, (b) general principles of equity (regardless of whether enforceability is considered in a proceeding in equity or at law), and (c) the requirements that a claim with respect to any Senior Debt Securities denominated other than in United States dollars (or a judgment denominated other than in United States dollars in respect to the claims) be converted into United States dollars at a rate of exchange prevailing on a date determined by applicable law.

The opinions expressed above are limited to the laws of the State of New York and the federal laws of the United States of America. Our opinions are rendered only with respect to the laws, and the rules, regulations and orders under those laws, that are currently in effect. We express no opinion with respect to the enforceability of any indemnity against any loss in converting into a specified currency the proceeds or amount of a court judgment in another currency.

We hereby consent to use of this opinion as an exhibit to the Company’s current report on Form 6-K submitted to the U.S. Securities and Exchange Commission (the “Commission”) in connection with the offer and sale of the Senior Debt Securities and the incorporation by reference of this opinion into the Registration Statement. We also consent to the use of our name under the heading “Legal Matters” in the Final Prospectus Supplement forming a part of the Registration Statement. In giving this consent, we do not hereby admit that we come within the category of persons whose consent is required by the Securities Act of 1933, as amended, or the rules and regulations of the Commission thereunder.