Notes - Segment Information
| Concept | 2024-01-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | 2024-01-01 to 2024-03-31 | 2024-01-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | As at 2024-03-31 | 2023-10-01 to 2024-03-31 | 2024-01-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | 2024-01-01 to 2024-03-31 | 2024-01-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | As at 2023-09-30 | 2023-01-01 to 2023-03-31 | 2022-10-01 to 2023-03-31 | 2023-01-01 to 2023-03-31 | 2022-10-01 to 2023-03-31 | 2023-01-01 to 2023-03-31 | 2022-10-01 to 2023-03-31 | 2022-10-01 to 2023-03-31 | 2022-10-01 to 2023-03-31 | 2023-01-01 to 2023-03-31 | 2023-01-01 to 2023-03-31 | 2023-01-01 to 2023-03-31 | 2022-10-01 to 2023-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Notes - Segment information | ||||||||||||||||||||||||||
| Segment information | ||||||||||||||||||||||||||
| Revenue | ||||||||||||||||||||||||||
| Revenue from external customers | 
                                                9,169,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,102,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,177,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,986,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,575,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,079,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                17,360,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,169,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                608,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,360,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,883,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,462,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,959,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,419,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,168,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,168,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,704,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,326,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intersegment revenue | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Revenue | 
                                                9,169,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,106,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,177,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,986,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,577,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,079,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                17,360,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,172,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                608,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,364,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,883,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,464,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,963,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,419,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,168,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,173,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,587,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,704,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,326,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Segment profit (loss) | 
                                                127,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,095,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -252,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -123,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                399,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -732,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                117,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                123,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -152,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                110,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                887,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -223,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                733,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,333,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -17,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,170,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,164,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                884,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                168,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                55,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other income and expenses, net | 
                                                899,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                853,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                541,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Finance income and costs, net | 
                                                -38,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -82,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -18,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -33,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Share of profit (loss) of investments accounted for using equity method | 
                                                -39,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -75,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -42,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -112,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Profit (loss) before tax | 
                                                949,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                813,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                827,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
| Assets | — | — | — | — | — | — | 
                                                50,619,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                51,166,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Investments accounted for using equity method | — | — | — | — | — | — | 
                                                584,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                536,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
| Depreciation and amortization | 
                                                503,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                542,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                221,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                270,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                436,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,002,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                503,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,002,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                523,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                406,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                263,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                548,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                223,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,011,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,011,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                523,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                36,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                56,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |