Notes - Segment Information
| Concept | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Notes - Segment information | ||||||||||||||||||||
| Segment information | ||||||||||||||||||||
| Revenue | ||||||||||||||||||||
| Revenue from external customers | 
                                                138,654,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                160,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                21,577,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                160,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                148,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                148,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,150,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                125,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intersegment revenue | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Revenue | 
                                                138,654,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                160,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                21,577,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                160,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                148,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                148,255,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,150,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                125,105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) before tax | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                36,135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                33,616,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | — | 
                                                189,803,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                283,637,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                175,655,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                93,834,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,414,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                151,253,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                263,404,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                97,736,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                165,668,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Depreciation and amortization | 
                                                5,808,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,015,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                189,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,997,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,005,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                18,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,023,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                194,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,811,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Impairment losses | — | — | 
                                                849,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                722,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
| Capital expenditures | 
                                                30,864,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                31,027,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                163,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                31,027,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,430,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                16,430,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                207,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                16,223,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |