Key Financial Data Of Group
| Concept | As at 2023-09-30 | 2023-07-01 to 2023-09-30 | 2023-04-01 to 2023-09-30 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2022-07-01 to 2022-09-30 | As at 2022-09-30 | 2022-04-01 to 2022-09-30 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||
| Business results of group | ||||||||
| Revenue | — | 
                                                36,301,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                73,314,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                144,175,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                35,517,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                71,136,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) before tax | — | — | 
                                                21,146,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                30,489,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                19,398,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss), attributable to owners of parent | — | 
                                                7,426,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,176,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                22,812,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,972,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                15,222,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income, attributable to owners of parent | — | — | 
                                                19,679,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                22,854,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                14,585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Equity attributable to owners of parent | 
                                                211,466,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                195,625,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                191,197,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                249,499,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                237,451,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                225,374,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                110.26
                                                
                                             | 
                                                240.17
                                                
                                             | — | 
                                                338.70
                                                
                                             | 
                                                103.53
                                                
                                             | — | 
                                                226.01
                                                
                                             | 
| Diluted earnings (loss) per share | — | — |  | — |  | — | — |  | 
| Ratio of owners' equity to gross assets | 
                                                0.848
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.824
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.848
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Cash flows from (used in) operating activities | — | — | 
                                                7,938,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,170,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,817,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash flows from (used in) investing activities | — | — | 
                                                -1,693,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -17,631,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -5,882,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash flows from (used in) financing activities | — | — | 
                                                -4,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -9,605,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -4,911,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | 
                                                62,855,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                60,047,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                63,449,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |