Key Financial Data Of Group
| 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 | 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 | — | 
                                                3,016,061,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,016,061,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,322,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,322,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,667,991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,667,991,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,009,932,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,009,932,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,328,494,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                327,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                330,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                25,291,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                28,814,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -126,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -122,631,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -361,279,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -361,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                85,034,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | 
                                                331,268,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                22,569,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -157,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -364,622,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | 
                                                333,983,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                28,777,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -154,635,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -361,835,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | — | 
                                                3,457,844,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,445,066,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,113,626,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,124,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,095,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,092,208,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,250,208,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,250,060,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,543,507,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | 
                                                3,919,796,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,911,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,834,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,842,109,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,472,189,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,472,984,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,477,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,481,010,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,841,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | 
                                                1,099.42
                                                
                                             | 
                                                1,095.36
                                                
                                             | — | 
                                                989.95
                                                
                                             | 
                                                993.30
                                                
                                             | — | — | — | 
                                                983.23
                                                
                                             | 
                                                982.19
                                                
                                             | 
                                                1,032.07
                                                
                                             | — | — | 
                                                1,032.02
                                                
                                             | — |  | — | 
                                                1,131.88
                                                
                                             | 
| Basic earnings (loss) per share | — | 
                                                104.49
                                                
                                             | 
                                                105.33
                                                
                                             | — | — | 
                                                6.05
                                                
                                             | — | — | 
                                                7.17
                                                
                                             | 
                                                -51.01
                                                
                                             | 
                                                -49.93
                                                
                                             | — | — | — | 
                                                -116.11
                                                
                                             | 
                                                -116.03
                                                
                                             | — | 
                                                21.21
                                                
                                             | — |  | — | 
| Diluted earnings per share | — |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | 
                                                0.882
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.881
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.812
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.813
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.892
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.890
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.935
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.934
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.922
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                0.100
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.101
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.006
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.007
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.024
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                36.80
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                36.51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                454.40
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                383.40
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                93.91
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                660,976,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -37,573,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -39,923,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                36,360,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                84,386,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -500,029,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                465,910,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -77,348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                68,624,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -958,341,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -291,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -108,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -90,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,508,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,428,957,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | 
                                                2,603,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,435,996,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,002,540,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,112,353,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,995,095,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Number of employees | 
                                                63
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                63
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                43
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                64
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                63
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                42
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                39
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |