Notes - Segment Information
| Concept | 2024-10-01 to 2025-03-31 | 2024-10-01 to 2025-03-31 | 2024-10-01 to 2025-03-31 | As at 2025-03-31 | 2024-10-01 to 2025-03-31 | 2024-10-01 to 2025-03-31 | As at 2024-09-30 | 2023-10-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Notes - Segment information | ||||||||||||
| Segment information | ||||||||||||
| Revenue | ||||||||||||
| Revenue from external customers | 
                                                14,291,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,291,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,260,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,031,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,280,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,280,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,177,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,102,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intersegment revenue | 
                                                4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Revenue | 
                                                14,295,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,291,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,260,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,035,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,284,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,280,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,177,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,106,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Segment profit (loss) | 
                                                1,989,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,995,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -185,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,175,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                842,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                850,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -252,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,095,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other income and expenses, net | — | 
                                                -171,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                867,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Finance income and costs, net | — | 
                                                16,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -10,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share of profit (loss) of investments accounted for using equity method | — | 
                                                -38,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -75,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Profit (loss) before tax | — | 
                                                1,801,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,631,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Assets | — | — | — | 
                                                37,436,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                41,191,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
| Investments accounted for using equity method | — | — | — | 
                                                166,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                205,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
| Depreciation and amortization | 
                                                577,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                577,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                59,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                518,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                565,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                565,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                542,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |