Key Financial Data Of Group
| Concept | 2023-04-01 to 2024-03-31 | As at 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 | 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 group | ||||||||||||||||||||||
| Business results of group | ||||||||||||||||||||||
| Net sales | 
                                                812,850,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                816,701,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                790,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                794,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                603,855,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                647,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                531,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                602,749,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                500,062,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                576,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | 
                                                145,815,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                125,413,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                65,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -149,503,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -69,963,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -243,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -196,675,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -310,511,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -503,432,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -678,762,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                186,694,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -289,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -258,767,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -318,827,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -668,125,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | 
                                                186,694,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -289,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -258,767,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -318,827,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -668,125,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | — | 
                                                1,265,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,275,111,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,088,416,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,078,616,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,368,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,719,385,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,629,282,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,845,193,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,948,457,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,064,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                1,618,582,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,585,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,394,501,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,434,337,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,705,338,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,997,942,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,838,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,962,901,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,372,989,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,439,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                135.85
                                                
                                             | — | 
                                                136.91
                                                
                                             | — | 
                                                116.86
                                                
                                             | 
                                                115.81
                                                
                                             | — | — | — | 
                                                146.92
                                                
                                             | 
                                                184.61
                                                
                                             | 
                                                174.70
                                                
                                             | — | — | 
                                                197.88
                                                
                                             | — | 
                                                208.97
                                                
                                             | — | 
                                                221.41
                                                
                                             | 
| Basic earnings (loss) per share | 
                                                20.05
                                                
                                             | — | 
                                                20.05
                                                
                                             | — | — | — | 
                                                -67.74
                                                
                                             | — | — | 
                                                -31.10
                                                
                                             | 
                                                -13.27
                                                
                                             | 
                                                -27.78
                                                
                                             | — | — | — | 
                                                -23.52
                                                
                                             | 
                                                -34.23
                                                
                                             | — | 
                                                -62.24
                                                
                                             | — | 
                                                -76.00
                                                
                                             | — | 
| Diluted earnings per share |  | — |  | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                0.782
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.804
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.781
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.752
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.802
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.861
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.885
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.939
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.820
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.845
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | 
                                                0.158
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.159
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | 
                                                26.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                26.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                133,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                26,458,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -93,204,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -194,145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -608,746,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -24,496,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                30,036,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -155,629,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -17,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,818,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                143,998,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -216,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                81,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                674,969,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                561,997,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                449,184,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                552,022,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                974,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | — | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                59
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                63
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                65
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                58
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                65
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | — | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |