そーせいグループ（4565） – (Correction) Partial corrections of “Notice Regarding Determination of Payment Amount and Other Matters of Issuance of New Shares Under RSU Plan”

PRESS RELEASE (Correction) Partial corrections of “Notice Regarding Determination of Payment Amount and Other Matters of Issuance of New Shares Under Restricted Stock Unit (RSU) Plan” Tokyo, Japan and Cambridge, UK, 20 April 2022 – Sosei Group Corporation (“the Company”; TSE: 4565) announces it has made partial corrections of “Notice Regarding Determination of Payment Amount and Other Matters of Issuance of New Shares Under Restricted Stock Unit (RSU) Plan” announced on April 8, 2022, as per below. The corrected parts are shown with underlines. [Before the correction] (1) Payment date (2) Type and number of shares to be issued 19 May 2022 207,030 shares of the Company’s common stock 1,427 Yen per share 295,431,810 Yen (3) Payment amount (4) Total amount of payment (5) Allottees (6) Other details [After the correction] (1) Payment date (2) Type and number of shares to be issued (3) Payment amount (4) Total amount of payment (5) Allottees (6) Other details 7 Directors and Executive Officers of the Company 52 Directors of subsidiaries of the Company and employees of the Company and its subsidiaries The Securities Registration Statement relating to the Share Issuance has been filed in accordance with the Financial Instruments and Exchange Act. 19 May 2022 208,392 shares of the Company’s common stock 1,427 Yen per share 297,375,384 Yen 7 Directors and Executive Officers of the Company 53 Directors of subsidiaries of the Company and employees of the Company and its subsidiaries The Securities Registration Statement relating to the Share Issuance has been filed in accordance with the Financial Instruments and Exchange Act. -ENDS- PRESS RELEASE About Sosei Heptares We are an international biopharmaceutical group focused on the discovery and early development of new medicines originating from our proprietary GPCR-targeted StaR® technology and structure-based drug design platform capabilities. We are advancing a broad and deep pipeline of novel medicines across multiple therapeutic areas, including neurology, immunology, gastroenterology, and inflammatory diseases. We have established partnerships with some of the world’s leading pharmaceutical companies and multiple emerging biotechnology companies, including AbbVie, AstraZeneca, Biohaven, Genentech (Roche), GSK, Neurocrine Biosciences, Novartis, Pfizer, Takeda and Verily. Sosei Heptares is headquartered in Tokyo, Japan with corporate and R&D facilities in Cambridge, UK. “Sosei Heptares” is the corporate brand and trademark of Sosei Group Corporation, which is listed on the Tokyo Stock Exchange (ticker: 4565). Sosei, Heptares, the logo and StaR® are trademarks of Sosei Group companies. For more information, please visit https://soseiheptares.com/ LinkedIn: @soseiheptaresco | Twitter: @soseiheptaresco | YouTube: @soseiheptaresco Enquiries: Sosei Heptares – Media and Investor Relations Hironoshin Nomura, CFO +81 (0)3 6679 2178 | Hironoshin.Nomura@SoseiHeptares.com Shinichiro Nishishita, VP Investor Relations, Head of Regulatory Disclosures +81 (0)3 5210 3399 | IR@SoseiHeptares.com MEDiSTRAVA Consulting (for International Media) Mark Swallow, David Dible, Eleanor Perkin +44 (0)203 928 6900| SoseiHeptares@medistrava.com Forward-looking statements This press release contains forward-looking statements, including statements about the discovery, development, and commercialization of products. Various risks may cause Sosei Group Corporation’s actual results to differ materially from those expressed or implied by the forward-looking statements, including: adverse results in clinical development programs; failure to obtain patent protection for inventions; commercial limitations imposed by patents owned or controlled by third parties; dependence upon strategic alliance partners to develop and commercialize products and services; difficulties or delays in obtaining regulatory approvals to market products and services resulting from development efforts; the requirement for substantial funding to conduct research and development and to expand commercialization activities; and product initiatives by competitors. As a result of these factors, prospective investors are cautioned not to rely on any forward-looking statements. We disclaim any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.