Key Financial Data Of Reporting Company
| Concept | As at 2024-12-31 | 2024-07-01 to 2024-12-31 | 2023-07-01 to 2024-06-30 | As at 2024-06-30 | As at 2023-12-31 | 2023-07-01 to 2023-12-31 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Net sales | — | 
                                                3,077,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,125,104,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,027,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | 
                                                343,674,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                547,695,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                274,114,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                4,413,078,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,266,003,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,267,212,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                6,257,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,269,107,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,706,712,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                41.28
                                                
                                             | 
                                                33.34
                                                
                                             | — | — | 
                                                30.43
                                                
                                             | 
| Diluted earnings per share | — | 
                                                41.27
                                                
                                             | 
                                                33.31
                                                
                                             | — | — | 
                                                30.40
                                                
                                             | 
| Equity-to-asset ratio | 
                                                0.694
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.670
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.727
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                22,607,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                826,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                271,540,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | 
                                                -52,781,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -292,542,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -116,269,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | 
                                                -208,143,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                217,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -174,179,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | 
                                                3,375,375,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,613,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,817,651,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — |