Collaborations, Licensing Arrangements, Other Asset Acquisitions, and Others - Summary of Payments Made Under the Terms of Collaboration and Licensing Arrangements (Details) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
|
| Collaborations, Licensing Arrangements, Other Asset Acquisitions, and Others [Abstract] | |||
| Initial up-front payments, milestone payments, and other asset acquisitions | ¥ 87,129 | ¥ 124,878 | ¥ 676,156 |
| Acquisition of shares of collaboration and in-licensing partners | ¥ 12,268 | ¥ 2,050 | ¥ 494 |