Press release
May 10, 2018

Notice of Changes in Accounting Period (End of Business Year)

Tokyo, Japan and London, UK, 10 May 2018 – Sosei Group Corporation (“Sosei” or the “Company”; TSE Mothers Index: 4565), the world leader in GPCR medicine design and development, today announced that its Board of Directors has resolved to change the fiscal year end, subject to the approval of the “Proposal for Partial Amendment to the Articles of Incorporation” at the 28th Ordinary General Meeting of Shareholders to be held in late June 2018.

1. Reason for Change
   1.1. The Company is aligning its fiscal year end to be in line with our global peer group including the major pharmaceutical companies that we partner and collaborate with on a                          global basis.
2. Details of Change in Fiscal Year End
    2.1. Current accounting period: As of March 31 of each year
    2.2. After the change: December 31 of each year
            Note: The 29th fiscal year, the transitional period for the change in fiscal year-end, will be nine months from April 1, 2018 to December 31, 2018.
3. Future Outlook
    3.1. Please refer to future outlook in the summary of earnings report for FY2017 disclosed today.
4. Amendment to Articles of Incorporation
    4.1. We will disclose the “Proposal for amendment to the Articles of Incorporation” promptly after the proposal is determined at the board of directors meeting scheduled for May            
           15, 2018 as part of the proposals to be submitted to the 28th Annual General Meeting of Shareholders to be held in June 2018.