Key Financial Data Of Reporting Company
| Concept | As at 2024-12-31 | 2024-07-01 to 2024-12-31 | As at 2024-06-30 | 2023-07-01 to 2024-06-30 | 2023-07-01 to 2023-12-31 | As at 2023-12-31 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Ordinary profit (loss) | — | 
                                                -479,647,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,208,349,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -393,340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | 
                                                -480,272,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,209,599,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -393,965,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Equity in earnings (losses) of affiliates if equity method is applied | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | 
                                                8,166,177,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,585,635,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,585,635,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | 
                                                19,113,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                18,023,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                18,023,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                3,021,174,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,340,867,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,150,667,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                3,131,909,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,432,855,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,271,809,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Dividend paid per share | — |  | — |  |  | — | 
| Basic earnings (loss) per share | — | 
                                                -25.77
                                                
                                             | — | 
                                                -67.90
                                                
                                             | 
                                                -22.37
                                                
                                             | — | 
| Diluted earnings per share | — |  | — |  |  | — | 
| Equity-to-asset ratio | 
                                                0.953
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.947
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.954
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | — | 
                                                -170,537,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,280,192,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -374,201,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                1,150,682,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,538,270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,539,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                2,861,490,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,888,200,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,780,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |