v3.26.1
Financial Instruments - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - Recurring fair value measurement [member] - JPY (¥)
¥ in Millions
Mar. 31, 2026
Mar. 31, 2025
Disclosure of fair value measurement of assets [line items]    
Total Assets ¥ 687,957 ¥ 521,486
Total Liabilities 1,368 1,186
Derivative Liabilities | Financial liabilities measured at FVTPL    
Disclosure of fair value measurement of assets [line items]    
Total Liabilities 1,368 1,186
Level 1    
Disclosure of fair value measurement of assets [line items]    
Total Assets 262,455 137,560
Total Liabilities 100 102
Level 1 | Derivative Liabilities | Financial liabilities measured at FVTPL    
Disclosure of fair value measurement of assets [line items]    
Total Liabilities 100 102
Level 2    
Disclosure of fair value measurement of assets [line items]    
Total Assets 82,592 96,284
Total Liabilities 1,268 1,084
Level 2 | Derivative Liabilities | Financial liabilities measured at FVTPL    
Disclosure of fair value measurement of assets [line items]    
Total Liabilities 1,268 1,084
Level 3    
Disclosure of fair value measurement of assets [line items]    
Total Assets 342,910 287,642
Financial assets measured at FVTPL | Exchange Traded Funds    
Disclosure of fair value measurement of assets [line items]    
Total Assets 202,879 132,509
Financial assets measured at FVTPL | Exchange Traded Funds | Level 1    
Disclosure of fair value measurement of assets [line items]    
Total Assets 202,879 132,509
Financial assets measured at FVTPL | Equity Securities    
Disclosure of fair value measurement of assets [line items]    
Total Assets 1,294 184
Financial assets measured at FVTPL | Equity Securities | Level 1    
Disclosure of fair value measurement of assets [line items]    
Total Assets 306 184
Financial assets measured at FVTPL | Equity Securities | Level 2    
Disclosure of fair value measurement of assets [line items]    
Total Assets 24  
Financial assets measured at FVTPL | Equity Securities | Level 3    
Disclosure of fair value measurement of assets [line items]    
Total Assets 964  
Financial assets measured at FVTPL | Derivative Assets    
Disclosure of fair value measurement of assets [line items]    
Total Assets 2,310 2,234
Financial assets measured at FVTPL | Derivative Assets | Level 1    
Disclosure of fair value measurement of assets [line items]    
Total Assets 203 228
Financial assets measured at FVTPL | Derivative Assets | Level 2    
Disclosure of fair value measurement of assets [line items]    
Total Assets 2,107 2,006
Financial assets measured at FVTPL | Derivative Assets | Level 3    
Disclosure of fair value measurement of assets [line items]    
Total Assets   0
Financial assets measured at FVTOCI | Japanese Government Bonds and Municipal Bonds    
Disclosure of fair value measurement of assets [line items]    
Total Assets 58,674 11,425
Financial assets measured at FVTOCI | Japanese Government Bonds and Municipal Bonds | Level 1    
Disclosure of fair value measurement of assets [line items]    
Total Assets 55,949 4,639
Financial assets measured at FVTOCI | Japanese Government Bonds and Municipal Bonds | Level 2    
Disclosure of fair value measurement of assets [line items]    
Total Assets 2,725 6,786
Financial assets measured at FVTOCI | Corporate and Other Debt Securities    
Disclosure of fair value measurement of assets [line items]    
Total Assets 87,586 95,692
Financial assets measured at FVTOCI | Corporate and Other Debt Securities | Level 1    
Disclosure of fair value measurement of assets [line items]    
Total Assets 3,118  
Financial assets measured at FVTOCI | Corporate and Other Debt Securities | Level 2    
Disclosure of fair value measurement of assets [line items]    
Total Assets 77,736 87,492
Financial assets measured at FVTOCI | Corporate and Other Debt Securities | Level 3    
Disclosure of fair value measurement of assets [line items]    
Total Assets 6,732 8,200
Financial assets measured at FVTOCI | Asset Backed Securities    
Disclosure of fair value measurement of assets [line items]    
Total Assets 335,214 279,442
Financial assets measured at FVTOCI | Asset Backed Securities | Level 3    
Disclosure of fair value measurement of assets [line items]    
Total Assets ¥ 335,214 ¥ 279,442