Key Financial Data Of Reporting Company
| Concept | 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 | 2018-10-01 to 2019-09-30 | As at 2019-09-30 | 2018-10-01 to 2019-09-30 | As at 2019-09-30 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||||||||||||||
| Business results of reporting company | ||||||||||||||||||||
| Net sales | — | 
                                                34,467,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                37,304,148,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,958,370,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                33,674,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                29,722,259,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                32,506,681,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                28,252,586,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                30,120,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                26,776,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                28,480,784,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | 
                                                2,579,628,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,970,096,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,268,205,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,744,457,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,117,276,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,563,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,026,181,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,284,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,387,613,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,581,514,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | 
                                                1,594,634,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,388,009,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,456,883,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,627,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                987,173,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | 
                                                1,673,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,673,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,673,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,673,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,673,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | 
                                                18,614,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | 
                                                18,614,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                18,614,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | 
                                                18,614,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                18,614,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | 
                                                16,963,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                20,021,181,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                15,538,966,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,397,777,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,673,177,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                17,281,228,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,445,686,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,645,530,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                14,024,443,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,926,577,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | 
                                                31,311,318,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                33,687,311,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                29,358,714,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                31,533,808,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,994,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                28,911,596,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                26,206,151,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,993,832,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                24,683,350,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,634,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | 
                                                935.11
                                                
                                             | — | 
                                                1,093.81
                                                
                                             | — | — | 
                                                856.56
                                                
                                             | 
                                                1,005.57
                                                
                                             | — | 
                                                808.83
                                                
                                             | — | 
                                                944.94
                                                
                                             | — | — | 
                                                745.48
                                                
                                             | 
                                                860.60
                                                
                                             | — | — | 
                                                771.23
                                                
                                             | — | 
                                                661.26
                                                
                                             | 
| Dividend paid per share | — | 
                                                31.00
                                                
                                             | — | — | 
                                                28.00
                                                
                                             | — | — | — | — | 
                                                25.00
                                                
                                             | — | — | 
                                                24.00
                                                
                                             | — | — | — | 
                                                12.00
                                                
                                             | — | — | — | 
| Interim dividend paid per share | — |  | — | — |  | — | — | — | — |  | — | — |  | — | — | — |  | — | — | — | 
| Basic earnings (loss) per share | — | 
                                                87.90
                                                
                                             | — | 
                                                102.18
                                                
                                             | 
                                                76.52
                                                
                                             | — | — | 
                                                95.52
                                                
                                             | — | 
                                                80.46
                                                
                                             | — | 
                                                95.82
                                                
                                             | 
                                                90.23
                                                
                                             | — | — | 
                                                97.58
                                                
                                             | 
                                                54.74
                                                
                                             | — | 
                                                60.08
                                                
                                             | — | 
| Diluted earnings per share | — |  | — |  |  | — | — |  | — |  | — |  |  | — | — |  |  | — |  | — | 
| Equity-to-asset ratio | 
                                                0.542
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.587
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.529
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.577
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.544
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.591
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.513
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.553
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.562
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.505
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | 
                                                0.098
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.097
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.092
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.098
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.104
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.106
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.120
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.089
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.084
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | 
                                                10.22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.79
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.93
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.96
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11.61
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9.75
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.59
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                10.72
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.61
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9.67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | 
                                                0.353
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.366
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.311
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.266
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.219
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | 
                                                4,913,073,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                878,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,181,206,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,495,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                503,878,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | 
                                                -1,864,783,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,643,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,299,635,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,208,595,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,192,713,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | 
                                                -480,567,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -794,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -378,155,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -438,751,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -17,145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | 
                                                8,093,645,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,524,824,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,071,668,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,564,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,614,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                1,264
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,636
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,224
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,587
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,183
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,547
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,131
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,483
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,321
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,098
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                430
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                734
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                413
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                686
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                394
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                664
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                392
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                658
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                650
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                394
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | 
                                                1.490
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                1.243
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.457
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                1.584
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.868
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | 
                                                1.445
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                1.113
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.199
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.940
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.896
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |