v3.26.1
Bonds and Loans - Schedule of Composition of Loans (Details)
¥ in Millions, $ in Millions
Mar. 31, 2026
JPY (¥)
Mar. 31, 2025
JPY (¥)
Mar. 31, 2025
USD ($)
Disclosure of detailed information about borrowings [line items]      
JPY (millions) Carrying amount ¥ 225,026 ¥ 324,633  
Bilateral Loans      
Disclosure of detailed information about borrowings [line items]      
Principal amount in contractual currency (millions) 185,000    
JPY (millions) Carrying amount ¥ 185,000 210,000  
Bilateral Loans | Minimum      
Disclosure of detailed information about borrowings [line items]      
Interest rate (%) 0.513%    
Bilateral Loans | Maximum      
Disclosure of detailed information about borrowings [line items]      
Interest rate (%) 2.616%    
2025 USD Bilateral Loan      
Disclosure of detailed information about borrowings [line items]      
Principal amount in contractual currency (millions) | $     $ 500
JPY (millions) Carrying amount ¥ 0 74,505  
Interest rate (%) 4.71492%    
2024 Syndicated Hybrid Loans (Subordinated Loans)      
Disclosure of detailed information about borrowings [line items]      
Principal amount in contractual currency (millions) ¥ 40,000    
JPY (millions) Carrying amount ¥ 40,000 40,000  
2024 Syndicated Hybrid Loans (Subordinated Loans) | Tokyo Interbank Offered Rate (TIBOR) | Minimum      
Disclosure of detailed information about borrowings [line items]      
Interest rate (%) 1.35%    
2024 Syndicated Hybrid Loans (Subordinated Loans) | Tokyo Interbank Offered Rate (TIBOR) | Maximum      
Disclosure of detailed information about borrowings [line items]      
Interest rate (%) 2.35%    
Other      
Disclosure of detailed information about borrowings [line items]      
JPY (millions) Carrying amount ¥ 26 ¥ 128