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 | 
                                                59,390,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                100,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                50,937,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -427,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -879,380,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -429,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | 
                                                -495,433,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,104,460,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -633,487,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Equity in earnings (losses) of affiliates if equity method is applied | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | — | 
                                                2,436,148,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,971,019,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,939,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | 
                                                14,740,500
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                11,936,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                11,759,400
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | 
                                                1,838,254,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,398,344,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,783,942,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                2,191,325,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,693,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,989,786,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Dividend paid per share |  | — | — |  |  | — | 
| Basic earnings (loss) per share | 
                                                -35.90
                                                
                                             | — | — | 
                                                -93.69
                                                
                                             | 
                                                -53.87
                                                
                                             | — | 
| Diluted earnings per share |  | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.8027
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.7818
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.8703
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                -312,460,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -833,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -464,745,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -52,089,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -150,343,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -129,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                919,892,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                63,943,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                2,086,449,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,541,419,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,866,008,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |