Key Financial Data Of Group
| Concept | As at 2024-03-31 | 2024-01-01 to 2024-03-31 | 2023-10-01 to 2024-03-31 | As at 2023-09-30 | 2022-10-01 to 2023-09-30 | 2023-01-01 to 2023-03-31 | As at 2023-03-31 | 2022-10-01 to 2023-03-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||
| Business results of group | ||||||||
| Revenue | — | 
                                                9,169,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,360,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                36,405,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                19,168,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) before tax | — | — | 
                                                813,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,518,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss), attributable to owners of parent | — | 
                                                519,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                119,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                939,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                560,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,124,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income, attributable to owners of parent | — | — | 
                                                676,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,752,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,358,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Equity attributable to owners of parent | 
                                                32,514,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                32,456,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                31,112,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                50,619,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                51,166,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                49,782,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                4.06
                                                
                                             | 
                                                0.93
                                                
                                             | — | 
                                                7.31
                                                
                                             | 
                                                4.38
                                                
                                             | — | 
                                                8.72
                                                
                                             | 
| Diluted earnings (loss) per share | — | — | 
                                                0.93
                                                
                                             | — | 
                                                7.30
                                                
                                             | — | — | 
                                                8.70
                                                
                                             | 
| Ratio of owners' equity to gross assets | 
                                                0.642
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.634
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.625
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Cash flows from (used in) operating activities | — | — | 
                                                -12,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,233,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,655,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash flows from (used in) investing activities | — | — | 
                                                74,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,743,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -990,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash flows from (used in) financing activities | — | — | 
                                                -1,593,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -5,079,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -4,497,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | 
                                                15,148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                16,510,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,791,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |