Key Financial Data Of Group
| Concept | As at 2024-09-30 | 2024-04-01 to 2024-09-30 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2023-09-30 | 2023-04-01 to 2023-09-30 | 
|---|---|---|---|---|---|---|
| Key financial data of group | ||||||
| Business results of group | ||||||
| Ordinary profit (loss) | — | 
                                                7,078,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,852,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,101,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) attributable to owners of parent | — | 
                                                5,673,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,602,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,626,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income | — | 
                                                6,342,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,597,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                11,866,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                152,609,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                151,562,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                140,968,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                238,499,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                266,494,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                256,028,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                173.85
                                                
                                             | 
                                                471.94
                                                
                                             | — | — | 
                                                199.51
                                                
                                             | 
| Diluted earnings per share | — |  |  | — | — |  | 
| Equity-to-asset ratio | 
                                                0.608
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.540
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.525
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                -16,711,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,738,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,677,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | 
                                                -2,526,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -2,267,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | 
                                                -5,923,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -5,545,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -2,386,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | 
                                                41,003,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                63,265,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                55,340,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |