Revenue - Summary of Revenue Recognized from Contracts with Customers and Other Sources (Parenthetical) (Details) - JPY (¥) ¥ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
|
| Revenue [abstract] | |||
| Guarantee fees | ¥ 20,747 | ¥ 18,163 | ¥ 14,707 |