Exhibit 5.1

June 26, 2024

Takeda Pharmaceutical Company Limited,

    1-1, Nihonbashi-Honcho 2-Chome,

    Chuo-ku, Tokyo 103-8668,

    Japan.

Ladies and Gentlemen:

In connection with the registration under the Securities Act of 1933 (the “Act”) of an unspecified initial principal amount or number of senior debt securities (the “Securities”) of Takeda Pharmaceutical Company Limited, a joint stock corporation organized under the laws of Japan (the “Company”), we, as your United States counsel, have examined such corporate records, certificates and other documents, and such questions of law, as we have considered necessary or appropriate for the purposes of this opinion.

Upon the basis of such examination, it is our opinion that, when the registration statement on Form F-3 (the “Registration Statement”) has become effective under the Act, the terms of the Securities and of their issuance and sale have been duly established in conformity with the Indenture, so as not to violate any applicable law or result in a default under or breach of any agreement or instrument binding upon the Company and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company, and the Securities have been duly executed and authenticated in accordance with the Indenture and issued and sold as contemplated in the Registration Statement, and assuming the Securities will constitute valid and legally binding obligations of the Company under the laws of Japan, the Securities will constitute valid and legally binding obligations of the Company, subject to bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws of general applicability relating to or affecting creditors’ rights and to general equity principles.

In rendering the foregoing opinion, we are not passing upon, and assume no responsibility for, any disclosure in any registration statement or any related prospectus or other offering material relating to the offer and sale of the Securities.

We note that, as of the date of this opinion, a judgment for money in an action based on a Security denominated in a foreign currency or currency unit in a Federal or state court in the United States ordinarily would be enforced in the United States only in United States dollars. The date used to determine the rate of conversion of the foreign currency or currency unit in which a particular Security is denominated into United States dollars will depend upon various factors, including which court renders the judgment.

Takeda Pharmaceutical Company Limited -2-

Under Section 27 of the New York Judiciary Law, a state court in the State of New York rendering a judgment on a Security would be required to render such judgment in the foreign currency or currency unit in which the Security is denominated, and such judgment would be converted into United States dollars at the exchange rate prevailing on the date of entry of the judgment.

The foregoing opinion is limited to the Federal laws of the United States and the laws of the State of New York, and we are expressing no opinion as to the effect of the laws of any other jurisdiction. With respect to all matters of Japanese law, we note that you have received an opinion, dated June 26, 2024, of Nishimura & Asahi (Gaikokuho Kyodo Jigyo).

We have relied as to certain factual matters on information obtained from public officials, officers of the Company and other sources believed by us to be responsible.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to us under the heading “Legal Matters” in the prospectus included in the Registration Statement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act.

Very truly yours,

/s/ SULLIVAN & CROMWELL LLP