v3.26.1
Intangible assets - Reconciliation of Carrying Amount (Details) - JPY (¥)
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period ¥ 2,529,000,000 [1] ¥ 788,000,000
Intangible assets and goodwill at end of period [1] 13,600,000,000 2,529,000,000
Intangible assets pledged as security for liabilities 0 0
Internally generated intangible assets    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 1,162,000,000 788,000,000
Intangible assets and goodwill at end of period 1,759,000,000 1,162,000,000
Goodwill | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 1,117,000,000 0
Intangible assets and goodwill at end of period 9,502,000,000 1,117,000,000
Trademark / Trade Name | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 10,000,000 0
Intangible assets and goodwill at end of period 136,000,000 10,000,000
Customer Relationships | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 170,000,000 0
Intangible assets and goodwill at end of period 904,000,000 170,000,000
Developed Technology | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 70,000,000 0
Intangible assets and goodwill at end of period 713,000,000 70,000,000
Others | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Intangible assets and goodwill at end of period 0 0
Licences [member] | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Intangible assets and goodwill at end of period 586,000,000 0
Total gross carrying amount    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 3,286,000,000 1,331,000,000
Additions (not by business combination) 1,081,000,000 524,000,000
Additions (business combination) 10,401,000,000 1,367,000,000
Additions (transferred from PP&E)   100,000,000
Disposals (220,000,000) (36,000,000)
Others 161,000,000  
Intangible assets and goodwill at end of period 14,709,000,000 3,286,000,000
Total gross carrying amount | Internally generated intangible assets    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 1,917,000,000 1,328,000,000
Additions (not by business combination) 1,081,000,000 524,000,000
Additions (business combination) 0 0
Additions (transferred from PP&E)   100,000,000
Disposals (220,000,000) (35,000,000)
Others 0  
Intangible assets and goodwill at end of period 2,778,000,000 1,917,000,000
Total gross carrying amount | Goodwill | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 1,117,000,000 0
Additions (not by business combination) 0 0
Additions (business combination) 8,310,000,000 1,117,000,000
Additions (transferred from PP&E)   0
Disposals 0 0
Others 74,000,000  
Intangible assets and goodwill at end of period 9,501,000,000 1,117,000,000
Total gross carrying amount | Trademark / Trade Name | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 10,000,000 0
Additions (not by business combination) 0 0
Additions (business combination) 123,000,000 10,000,000
Additions (transferred from PP&E)   0
Disposals 0 0
Others 5,000,000  
Intangible assets and goodwill at end of period 138,000,000 10,000,000
Total gross carrying amount | Customer Relationships | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 170,000,000 0
Additions (not by business combination) 0 0
Additions (business combination) 738,000,000 170,000,000
Additions (transferred from PP&E)   0
Disposals 0 0
Others 31,000,000  
Intangible assets and goodwill at end of period 939,000,000 170,000,000
Total gross carrying amount | Developed Technology | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 70,000,000 0
Additions (not by business combination) 0 0
Additions (business combination) 668,000,000 70,000,000
Additions (transferred from PP&E)   0
Disposals 0 0
Others 28,000,000  
Intangible assets and goodwill at end of period 766,000,000 70,000,000
Total gross carrying amount | Others | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 2,000,000 3,000,000
Additions (not by business combination) 0 0
Additions (business combination) 0 0
Additions (transferred from PP&E)   0
Disposals 0 (1,000,000)
Others 0  
Intangible assets and goodwill at end of period 2,000,000 2,000,000
Total gross carrying amount | Licences [member] | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Additions (not by business combination) 0 0
Additions (business combination) 562,000,000 0
Additions (transferred from PP&E)   0
Disposals 0 0
Others 23,000,000  
Intangible assets and goodwill at end of period 585,000,000 0
Accumulated depreciation and amortisation    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period (759,000,000) (544,000,000)
Disposals 0 2,000,000
Amortisation 353,000,000 217,000,000
Foreign currency translation 0  
Intangible assets and goodwill at end of period (1,111,000,000) (759,000,000)
Accumulated depreciation and amortisation | Internally generated intangible assets    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period (757,000,000) (541,000,000)
Disposals 0 1,000,000
Amortisation 263,000,000 217,000,000
Foreign currency translation 0  
Intangible assets and goodwill at end of period (1,020,000,000) (757,000,000)
Accumulated depreciation and amortisation | Goodwill | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Disposals 0 0
Amortisation 0 0
Foreign currency translation 0  
Intangible assets and goodwill at end of period 0 0
Accumulated depreciation and amortisation | Trademark / Trade Name | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Disposals 0 0
Amortisation 2,000,000 0
Foreign currency translation 0  
Intangible assets and goodwill at end of period (2,000,000) 0
Accumulated depreciation and amortisation | Customer Relationships | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Disposals 0 0
Amortisation 35,000,000 0
Foreign currency translation 0  
Intangible assets and goodwill at end of period (35,000,000) 0
Accumulated depreciation and amortisation | Developed Technology | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Disposals 0 0
Amortisation 53,000,000 0
Foreign currency translation 0  
Intangible assets and goodwill at end of period (53,000,000) 0
Accumulated depreciation and amortisation | Others | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period (2,000,000) (3,000,000)
Disposals 0 1,000,000
Amortisation 0 0
Foreign currency translation 0  
Intangible assets and goodwill at end of period (2,000,000) (2,000,000)
Accumulated depreciation and amortisation | Licences [member] | Not internally generated    
Disclosure of detailed information about intangible assets [line items]    
Intangible assets and goodwill at beginning of period 0 0
Disposals 0 0
Amortisation 0 0
Foreign currency translation 0  
Intangible assets and goodwill at end of period ¥ 0 ¥ 0
[1] Revised based on adjustments to the original provisional amounts made in March 2025 for Next Finance Tech’s identifiable assets acquired and liabilities assumed. Next Finance Tech was acquired by the Company in March 2025.