Key Financial Data Of Reporting Company
| Concept | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2022-04-01 to 2023-03-31 | As at 2023-03-31 | As at 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | As at 2022-03-31 | As at 2021-03-31 | 2020-04-01 to 2021-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | 2019-04-01 to 2020-03-31 | As at 2020-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | |||||||||||||||||||||||||||
| Business results of reporting company | |||||||||||||||||||||||||||
| Net sales | — | — | — | — | 
                                                42,313,155,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                61,056,247,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                33,108,161,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                46,459,747,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,573,739,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                49,153,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                37,453,188,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                48,633,913,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                47,239,492,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                58,074,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                2,722,269,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,085,761,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,511,848,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,998,053,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,647,028,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,700,696,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,136,220,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,447,538,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,990,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,132,289,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | 
                                                1,884,964,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                1,166,474,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,006,449,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                933,999,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,410,988,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | 
                                                5,195,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,195,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                5,195,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,195,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,195,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | 
                                                6,882,487
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                6,882,487
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,882,487
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                6,882,487
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                6,882,487
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | 
                                                25,714,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,158,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                23,129,216,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,256,208,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                24,696,592,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,389,405,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,982,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                23,035,669,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,468,326,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                22,667,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | 
                                                45,770,852,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                37,410,514,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                35,407,212,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                41,175,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                40,228,528,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                36,384,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                39,988,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                35,489,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                44,839,422,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                41,394,093,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | 
                                                4,359.43
                                                
                                             | — | 
                                                3,926.00
                                                
                                             | — | — | 
                                                3,946.61
                                                
                                             | 
                                                4,309.72
                                                
                                             | — | — | — | 
                                                3,897.53
                                                
                                             | 
                                                3,691.14
                                                
                                             | 
                                                3,671.05
                                                
                                             | — | — | 
                                                3,526.14
                                                
                                             | — | 
                                                3,592.33
                                                
                                             | — | 
                                                3,469.78
                                                
                                             | 
| Dividend paid per share | — | — | — | — | 
                                                128.00
                                                
                                             | — | — | — | — | — | — | 
                                                82.00
                                                
                                             | — | — | — | 
                                                76.00
                                                
                                             | — | — | — | — | 
                                                72.00
                                                
                                             | — | — | 
                                                70.00
                                                
                                             | — | — | — | 
| Interim dividend paid per share | — | — | — | — |  | — | — | — | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — |  | — | — | — | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                322.33
                                                
                                             | — | 
                                                335.66
                                                
                                             | — | — | — | — | 
                                                195.34
                                                
                                             | — | — | 
                                                246.01
                                                
                                             | 
                                                157.01
                                                
                                             | 
                                                151.99
                                                
                                             | — | — | — | 
                                                142.97
                                                
                                             | 
                                                174.43
                                                
                                             | — | 
                                                215.98
                                                
                                             | — | 
                                                226.10
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | 
                                                311.21
                                                
                                             | — | 
                                                324.08
                                                
                                             | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | 
                                                0.562
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.619
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.653
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.613
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.614
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.643
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.600
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.649
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.523
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.548
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                0.081
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.077
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.050
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.059
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.043
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.040
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.041
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.048
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.063
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.064
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                13.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                13.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                9.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                14.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                7.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                7.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | 
                                                0.397
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                0.420
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.484
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.504
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.324
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | 
                                                3,006,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                719,548,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -533,453,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                7,501,057,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -563,501,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | 
                                                -767,729,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -241,432,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                42,685,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,211,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                123,358,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | 
                                                -3,224,720,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -1,377,830,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -878,341,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -495,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -773,916,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | 
                                                10,661,321,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                11,453,824,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                12,066,710,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                12,983,881,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,218,187,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                580
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                650
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                792
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                792
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                580
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                589
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                743
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                744
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                590
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                747
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                587
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                756
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                593
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                216
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                219
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                219
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                197
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                172
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                177
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                175
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | 
                                                3.079
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.412
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.335
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.359
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | — | — | 
                                                1.278
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.047
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.091
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.248
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.879
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |