Key Financial Data Of Group
| Concept | 2024-10-01 to 2025-03-31 | As at 2025-03-31 | 2023-10-01 to 2024-09-30 | As at 2024-09-30 | 2023-10-01 to 2024-03-31 | As at 2024-03-31 | 
|---|---|---|---|---|---|---|
| Key financial data of group | ||||||
| Business results of group | ||||||
| Net sales | 
                                                35,928,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                80,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                43,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -511,740,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -754,961,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -365,471,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                1,608,710,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,108,192,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,322,294,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                2,290,108,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,757,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,912,050,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                -75.15
                                                
                                             | — | 
                                                -118.21
                                                
                                             | — | 
                                                -60.21
                                                
                                             | — | 
| Diluted earnings per share |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | 
                                                0.692
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.758
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.793
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                -404,516,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -661,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -315,253,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -155,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -121,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -121,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                1,047,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                838,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                668,409,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                1,258,345,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,816,943,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,993,032,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |