Key Financial Data Of Reporting Company
| Concept | 2024-04-01 to 2024-09-30 | As at 2024-09-30 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2023-09-30 | As at 2023-09-30 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Net sales | 
                                                56,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                72,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                44,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -537,786,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,158,929,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -551,566,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | 
                                                -538,736,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,168,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -553,922,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Equity in earnings (losses) of affiliates if equity method is applied | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | — | 
                                                1,047,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                650,661,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                362,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | 
                                                83,791,300
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                70,741,300
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                62,891,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | 
                                                1,234,107,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                978,987,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,013,618,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                1,696,224,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,230,257,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,163,667,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Dividend paid per share |  | — | — |  |  | — | 
| Basic earnings (loss) per share | 
                                                -7.11
                                                
                                             | — | — | 
                                                -18.21
                                                
                                             | 
                                                -8.81
                                                
                                             | — | 
| Diluted earnings per share |  | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.714
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.777
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.854
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                -520,584,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,156,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -466,327,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -7,648,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,454,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                1,002,619,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                690,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                1,539,394,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,057,360,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,063,188,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |