SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 4)*

WAVE Life Sciences Ltd.

(Name of Issuer)

Ordinary Shares

(Title of Class of Securities)

Y95308105

(CUSIP Number)

Katsunori Nagakari

1-10 Yamanokuchi-cho, Kagoshima City, Kagoshima, 892-0844, Japan

+81 99 295 6151

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

September 22, 2020

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box  ☐.

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7(b) for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act by shall be subject to all other provisions of the Act (however, see the Notes).

Page 1 of 5

CUSIP No. Y95308105

Page 2 of 5

CUSIP No. Y95308105

Page 3 of 5

Explanatory Note: This Amendment No. 4 (this “Statement”) to the Schedule 13D (the “Initial 13D”) filed by the Reporting Persons (as defined below) with the U.S. Securities and Exchange Commission (the “SEC”) on November 25, 2015, as amended and supplemented by Amendment No. 1 to the Initial 13D filed on March 31, 2017, Amendment No. 2 to the Initial 13D filed on March 22, 2018, and Amendment No. 3 to the Initial 13D filed on March 14, 2019, amends and supplements the items set forth herein. As used in this Schedule 13D, as amended hereby, the term “Reporting Persons” collectively refers to Kagoshima Shinsangyo Sousei Investment Limited Partnership (“KSS”) and Kagoshima Development Co. Ltd. (“Kagoshima Development Co.”).

Item 5. Interest in Securities of the Issuer.

Items 5(a), (b), (c) and (e) are hereby amended and restated as follows:

(a) and (b) The information relating to the beneficial ownership of the Issuer’s Ordinary Shares by each of the Reporting Persons set forth in Rows 7 through 13 of the cover pages hereto is incorporated herein by reference. The information in this Item 5(a) and in Row 13 of each cover page to this Statement with respect to the Reporting Persons is based on an aggregate of 61,249,222 shares of the Issuer’s Ordinary Shares issued and outstanding as of May 9, 2022, as reported in the Issuer’s Quarterly Report on Form 10-Q, as filed with the SEC on May 10, 2022.

(c) The Reporting Persons effected the following transactions in the Issuer’s Ordinary Shares on the dates indicated, and such transactions are the only transactions in the Issuer’s Ordinary Shares by the Reporting Persons in the sixty days preceding the filing of this Statement, or since the last 13D filing, whichever is less:

(e) As a result of additional issuances of Ordinary Shares by the Issuer to persons other than the Reporting Persons, the Reporting Persons ceased to be beneficial owners of more than five percent of the Ordinary Shares of the Company. Accordingly, this Statement represents the final amendment to the Schedule 13D and constitutes an exit filing for the Reporting Persons.

Page 4 of 5

SIGNATURE

After reasonable inquiry and to the best of their knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.