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 | 
                                                2,221,645,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,386,896,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,209,911,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                151,779,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                207,396,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                118,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                4,387,648,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,276,130,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,233,638,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                5,914,975,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,909,786,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,881,450,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                51.93
                                                
                                             | — | — | 
                                                78.44
                                                
                                             | 
                                                48.99
                                                
                                             | — | 
| Diluted earnings per share |  | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.742
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.724
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.720
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | 
                                                59,399,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                374,083,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                50,780,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -107,944,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -94,237,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -28,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                -36,244,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -30,131,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                63,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                1,984,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,052,891,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,913,990,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |