Key Financial Data Of Group
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 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 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||||||||||||||||||||||
| Business results of group | ||||||||||||||||||||||||||||
| Net sales | — | — | — | — | 
                                                7,957,457,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                7,727,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,381,201,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,392,457,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,042,905,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,070,463,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,602,058,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,638,727,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,383,489,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,417,643,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                51,583,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                54,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                129,639,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                153,574,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                198,702,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                242,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                215,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                237,370,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                309,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                288,370,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | — | 
                                                28,185,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                98,290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                156,042,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                159,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                169,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | — | 
                                                41,492,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                90,679,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                144,347,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                160,218,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                207,605,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | 
                                                2,186,880,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,991,908,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,187,079,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,997,052,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,952,359,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,138,092,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,035,437,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,881,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,920,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,775,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | 
                                                7,126,124,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                6,386,420,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                7,050,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,198,650,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,394,987,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,073,371,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,593,521,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,740,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,378,494,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,632,611,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | 
                                                523.35
                                                
                                             | — | — | — | — | — | — | 
                                                477.78
                                                
                                             | — | — | — | — | — | 
                                                523.57
                                                
                                             | 
                                                479.01
                                                
                                             | — | 
                                                468.29
                                                
                                             | 
                                                512.11
                                                
                                             | — | — | — | 
                                                487.68
                                                
                                             | 
                                                451.41
                                                
                                             | 
                                                460.17
                                                
                                             | — | — | 
                                                425.76
                                                
                                             | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                6.76
                                                
                                             | — | — | — | — | — | — | 
                                                9.07
                                                
                                             | 
                                                21.53
                                                
                                             | 
                                                23.58
                                                
                                             | — | — | 
                                                29.88
                                                
                                             | — | — | 
                                                37.43
                                                
                                             | 
                                                36.41
                                                
                                             | 
                                                38.27
                                                
                                             | — | — | — | 
                                                34.38
                                                
                                             | 
                                                40.77
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — |  | — | — | — | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | 
                                                0.306
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                0.312
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.310
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.322
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.362
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.352
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.363
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.397
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.357
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.383
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                0.013
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                0.019
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.045
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.046
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.065
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.075
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.083
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.081
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.085
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.093
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                150.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                112.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                48.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                35.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                27.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                29.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                28.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                35.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                30.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | 
                                                725,072,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                393,242,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                449,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                364,319,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                785,867,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | 
                                                -451,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -1,114,318,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -708,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -497,265,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -332,930,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | 
                                                -4,323,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                637,682,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                172,907,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                72,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -144,656,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                968,035,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                696,356,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                779,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                866,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                926,888,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                332
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                294
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                225
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                163
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                263
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                232
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                320
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                250
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                238
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                303
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                298
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                235
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                288
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                220
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                158
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                150
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                78
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                73
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                86
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                145
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                161
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                87
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                161
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                99
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                177
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                97
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |