Key Financial Data Of Group
| Concept | As at 2024-09-30 | 2023-10-01 to 2024-09-30 | As at 2024-09-30 | 2023-10-01 to 2024-09-30 | As at 2023-09-30 | 2022-10-01 to 2023-09-30 | As at 2023-09-30 | 2022-10-01 to 2023-09-30 | 2021-10-01 to 2022-09-30 | As at 2022-09-30 | As at 2022-09-30 | 2021-10-01 to 2022-09-30 | As at 2021-09-30 | 2020-10-01 to 2021-09-30 | As at 2021-09-30 | 2020-10-01 to 2021-09-30 | 2019-10-01 to 2020-09-30 | As at 2020-09-30 | As at 2020-09-30 | 2019-10-01 to 2020-09-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | ||||||||||||||||||||
| Business results of group | ||||||||||||||||||||
| Net sales | — | 
                                                6,467,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,951,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,474,316,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,615,805,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,746,980,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,843,952,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,155,060,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                9,258,198,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,921,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                7,860,026,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | 
                                                344,329,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                534,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                514,794,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                830,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                237,726,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                584,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                42,219,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                485,231,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                56,828,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                320,538,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Profit (loss) attributable to owners of parent | — | — | — | 
                                                341,302,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                570,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                399,980,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                324,645,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                263,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Comprehensive income | — | — | — | 
                                                341,302,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                570,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                399,980,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                324,645,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                263,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                4,160,220,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,561,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,415,962,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,905,046,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,081,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,353,214,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,078,208,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,111,393,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,209,067,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,942,882,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | 
                                                6,394,735,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,141,819,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,206,868,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,419,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,828,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,995,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,825,584,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,834,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,968,148,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,498,805,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets per share | 
                                                389.46
                                                
                                             | — | 
                                                239.76
                                                
                                             | — | 
                                                226.24
                                                
                                             | — | 
                                                365.68
                                                
                                             | — | — | 
                                                196.16
                                                
                                             | 
                                                316.49
                                                
                                             | — | 
                                                192.38
                                                
                                             | — | 
                                                288.39
                                                
                                             | — | — | 
                                                201.48
                                                
                                             | 
                                                268.73
                                                
                                             | — | 
| Basic earnings (loss) per share | — | 
                                                21.65
                                                
                                             | — | 
                                                31.96
                                                
                                             | — | 
                                                33.43
                                                
                                             | — | 
                                                53.96
                                                
                                             | 
                                                15.20
                                                
                                             | — | — | 
                                                37.83
                                                
                                             | — | 
                                                2.32
                                                
                                             | — | 
                                                29.75
                                                
                                             | 
                                                7.83
                                                
                                             | — | — | 
                                                24.21
                                                
                                             | 
| Diluted earnings per share | — |  | — |  | — |  | — |  | 
                                                15.11
                                                
                                             | — | — | 
                                                37.61
                                                
                                             | — | 
                                                2.30
                                                
                                             | — | 
                                                29.52
                                                
                                             | 
                                                7.75
                                                
                                             | — | — | 
                                                23.97
                                                
                                             | 
| Equity-to-asset ratio | 
                                                0.6506
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.6183
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.5743
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.6083
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.5416
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.5579
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.5411
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.5319
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.5540
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.5332
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Rate of return on equity | — | 
                                                0.0929
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.0846
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.1576
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.1575
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0776
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.1241
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.0118
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.1076
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.0391
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.0934
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Price-earnings ratio | — | 
                                                16.72
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11.33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                15.32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9.49
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23.95
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                9.62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                245.69
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                19.16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                149.81
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                48.45
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | — | — | — | 
                                                280,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                445,581,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                447,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -106,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                534,092,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | — | — | 
                                                7,015,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -242,573,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -136,718,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -223,835,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -179,450,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | — | — | 
                                                -387,213,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -78,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -130,738,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -27,117,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                275,016,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | 
                                                1,686,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,787,203,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,661,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,478,978,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,836,904,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Number of employees | 
                                                111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                34
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                96
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                35
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                92
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                38
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                94
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                32
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                86
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Average number of temporary employees | 
                                                109
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                61
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                118
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                125
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                77
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                125
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                73
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                112
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — |