Key Financial Data Of Reporting Company
| Concept | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | |||||||||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||||||||
| Net sales | — | 
                                                1,693,562,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,208,744,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                201,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,009,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                232,249,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,249,612,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                219,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,404,897,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                340,468,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,517,542,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                -136,491,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -94,427,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                -2,771,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                56,781,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                154,588,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                16,873,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -275,790,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                84,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                470,554,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | 
                                                -80,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                119,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -69,366,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -115,380,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                124,601,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | — | — | — | 
                                                1,205,123,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,205,123,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,205,123,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,205,123,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,205,123,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | 
                                                9,456,500
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                9,456,500
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                9,456,500
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                9,456,500
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                9,456,500
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | 
                                                452,462,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                429,279,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                509,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                569,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                534,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                390,684,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                428,664,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                460,050,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                712,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                575,430,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                1,657,448,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,653,828,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1,043,138,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,656,558,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,794,626,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                845,763,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,695,849,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,096,660,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,294,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,175,272,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                47.85
                                                
                                             | — | — | 
                                                45.40
                                                
                                             | — | — | — | — | — | — | — | 
                                                53.92
                                                
                                             | 
                                                60.22
                                                
                                             | — | — | — | 
                                                56.50
                                                
                                             | 
                                                41.32
                                                
                                             | 
                                                45.33
                                                
                                             | — | — | 
                                                48.65
                                                
                                             | — | 
                                                75.40
                                                
                                             | — | 
                                                60.86
                                                
                                             | 
| Dividend paid per share | — |  | — | — | — | — | — | — | — | — | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — |  | — | — | — | 
| Interim dividend paid per share | — |  | — | — | — | — | — | — | — | — | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — |  | — | — | — | 
| Basic earnings (loss) per share | — | 
                                                -8.52
                                                
                                             | 
                                                -11.18
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                12.60
                                                
                                             | — | — | 
                                                4.37
                                                
                                             | 
                                                -7.34
                                                
                                             | 
                                                12.06
                                                
                                             | — | — | — | 
                                                -12.20
                                                
                                             | 
                                                -29.91
                                                
                                             | — | 
                                                13.18
                                                
                                             | — | 
                                                38.56
                                                
                                             | — | 
| Diluted earnings per share | — |  |  | — | — | — | — | — | — | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                0.2730
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.2596
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.4887
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.3437
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.2977
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.4619
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.2528
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.4195
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.3110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.4896
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                0.2646
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0748
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.2369
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.2428
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.6875
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                35.32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                101.83
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                35.07
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                51.14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                17.48
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                62,496,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                110,856,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                552,874,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,490,676,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,101,238,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -297,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                -127,632,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -39,492,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -35,108,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -76,007,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -2,788,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                133,382,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -214,467,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                326,918,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                217,297,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                550,443,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | 
                                                788,139,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                676,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                375,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,575,694,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                34
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                103
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                108
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                108
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                104
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | 
                                                0.392
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.561
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.791
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.850
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | 
                                                1.962
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                1.388
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.312
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.286
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.905
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |