Key Financial Data Of Reporting Company
| Concept | As at 2024-12-31 | 2024-07-01 to 2024-12-31 | As at 2024-06-30 | 2023-07-01 to 2024-06-30 | 2023-07-01 to 2023-12-31 | As at 2023-12-31 | 
|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||
| Business results of reporting company | ||||||
| Net sales | — | 
                                                890,463,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,652,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                638,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                63,372,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                344,020,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -17,215,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | 
                                                38,975,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                403,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -14,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Equity in earnings (losses) of affiliates if equity method is applied | — | 
                                                5,329,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,003,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,799,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | 
                                                53,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                52,103,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,131,848,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | 
                                                4,734,669
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                4,720,947
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                4,684,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                3,678,861,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,638,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,215,479,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                4,029,673,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,101,519,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,579,949,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Dividend paid per share | — |  | — |  |  | — | 
| Basic earnings (loss) per share | — | 
                                                8.25
                                                
                                             | — | 
                                                86.70
                                                
                                             | 
                                                -3.16
                                                
                                             | — | 
| Diluted earnings per share | — | 
                                                7.42
                                                
                                             | — | 
                                                77.26
                                                
                                             |  | — | 
| Equity-to-asset ratio | 
                                                0.913
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.887
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.898
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | — | 
                                                216,629,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                285,510,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -39,787,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -19,957,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -37,048,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -18,359,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -31,283,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,980,215,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,008,511,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                3,065,877,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,900,488,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,622,173,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |