Key Financial Data Of Reporting Company
| Concept | 2024-10-01 to 2025-03-31 | As at 2025-03-31 | As at 2024-09-30 | 2023-10-01 to 2024-09-30 | 2023-10-01 to 2024-03-31 | As at 2024-03-31 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Net sales | 
                                                7,624,310,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                16,709,494,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,359,164,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                -43,899,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                399,281,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                172,937,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                1,912,260,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,004,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,118,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                4,413,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,407,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,912,466,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                -5.91
                                                
                                             | — | — | 
                                                29.37
                                                
                                             | 
                                                9.75
                                                
                                             | — | 
| Diluted earnings per share |  | — | — | 
                                                29.36
                                                
                                             | 
                                                9.75
                                                
                                             | — | 
| Equity-to-asset ratio | — | 
                                                0.423
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.447
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.399
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                -51,502,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -91,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -11,730,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -193,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -21,345,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -9,637,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                65,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -480,358,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                1,973,546,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,152,744,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,524,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |