Key Financial Data Of Reporting Company
| Concept | As at 2025-02-28 | 2024-03-01 to 2025-02-28 | 2023-03-01 to 2024-02-29 | As at 2024-02-29 | 2022-03-01 to 2023-02-28 | As at 2023-02-28 | As at 2022-02-28 | 2021-04-01 to 2022-02-28 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||||
| Business results of reporting company | ||||||||||
| Net sales | — | 
                                                2,052,289,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,205,457,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,572,852,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,865,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,750,241,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                -278,838,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -371,162,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -117,094,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                133,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                927,484,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | 
                                                -437,770,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,281,854,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -133,340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                89,865,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                575,944,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Equity in earnings (losses) of affiliates if equity method is applied | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Share capital | 
                                                401,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                401,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                401,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                401,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                401,160,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | 
                                                2,963,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                2,963,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                2,963,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
                                                2,963,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                2,963,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                1,039,659,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,477,429,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,759,313,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,892,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,802,499,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                1,272,331,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,646,593,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,364,476,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,303,257,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,431,856,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                350.90
                                                
                                             | — | — | 
                                                498.65
                                                
                                             | — | 
                                                931.29
                                                
                                             | 
                                                976.29
                                                
                                             | — | — | 
                                                945.85
                                                
                                             | 
| Dividend paid per share | — |  |  | — |  | — | — |  |  | — | 
| Interim dividend paid per share | — |  |  | — |  | — | — |  |  | — | 
| Basic earnings (loss) per share | — | 
                                                -147.75
                                                
                                             | 
                                                -432.63
                                                
                                             | — | 
                                                -45.00
                                                
                                             | — | — | 
                                                30.33
                                                
                                             | 
                                                207.65
                                                
                                             | — | 
| Diluted earnings per share | — |  |  | — |  | — | — |  | 
                                                201.36
                                                
                                             | — | 
| Equity-to-asset ratio | 
                                                0.817
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.897
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.820
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.876
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.817
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                -0.348
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.605
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                -0.047
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.032
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.271
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                32.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                20.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                -209,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -398,402,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                536,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -672,048,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                48,187,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -15,367,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -114,786,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -76,425,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -8,444,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -20,213,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -71,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -250,171,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                92,339,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                157,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                645,591,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                658,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                883,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,646,673,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,094,274,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,617,756,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Number of employees | 
                                                45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                43
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |