Financial risk management - Summary of Foreign Exchange Risk Exposures (Detail) - Currency Risk That Are Unhedged By The Use Of Derivatives [Member] - JPY (¥) ¥ in Millions |
Mar. 31, 2025 |
Mar. 31, 2024 |
|---|---|---|
| U.S. dollar [member] | ||
| Disclosure of nature and extent of risks arising from financial instruments [line items] | ||
| Foreign exchange risk | ¥ 143,720 | ¥ 81,000 |
| Euro [member] | ||
| Disclosure of nature and extent of risks arising from financial instruments [line items] | ||
| Foreign exchange risk | ¥ (2,903) | ¥ 282 |