Key Financial Data Of Reporting Company
| Concept | 2023-04-01 to 2023-12-31 | As at 2023-12-31 | 2023-10-01 to 2023-12-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | As at 2022-12-31 | 2022-04-01 to 2022-12-31 | 2022-10-01 to 2022-12-31 | 
|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||
| Business results of reporting company | ||||||||
| Ordinary income | 
                                                295,912,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                331,323,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                248,298,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                59,449,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                50,050,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                47,301,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                965,024,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                901,750,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                833,834,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Total assets | — | 
                                                32,772,195,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,924,282,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                28,850,272,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Basic earnings (loss) per share | 
                                                330.01
                                                
                                             | — | 
                                                168.24
                                                
                                             | — | 
                                                165.54
                                                
                                             | — | 
                                                173.34
                                                
                                             | 
                                                10.06
                                                
                                             | 
| Diluted earnings per share |  | — | — | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.0294
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.0300
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.0288
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — |