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 | 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 | — | — | — | — | — | — | 
                                                95,895,663,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                91,574,995,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                86,292,937,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                85,811,424,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                85,989,819,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Operating revenue | — | — | — | — | 
                                                3,647,129,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,671,161,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,254,048,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,924,444,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,679,818,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                612,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,294,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                578,413,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,516,614,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,449,055,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,711,421,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                616,415,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,253,560,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                743,122,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,127,290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | 
                                                613,118,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                514,638,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,279,982,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                325,390,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                416,978,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | — | — | — | — | — | 
                                                1,299,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,299,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1,299,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,299,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,299,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | 
                                                10,377,999
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                10,987,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,987,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                10,987,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                10,987,200
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | 
                                                16,132,852,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,758,010,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,895,597,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,716,291,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                13,625,592,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,712,738,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,453,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,721,022,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,323,533,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,569,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | 
                                                51,183,847,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                33,342,634,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                32,041,812,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                48,694,862,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                46,320,923,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,159,580,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                43,187,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                27,943,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                40,154,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                24,920,798,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | 
                                                1,554.52
                                                
                                             | 
                                                747.54
                                                
                                             | — | 
                                                725.83
                                                
                                             | 
                                                1,352.85
                                                
                                             | — | — | — | 
                                                1,252.58
                                                
                                             | 
                                                709.02
                                                
                                             | 
                                                1,144.79
                                                
                                             | — | — | 
                                                617.85
                                                
                                             | — | 
                                                1,040.95
                                                
                                             | — | 
                                                603.94
                                                
                                             | 
| Dividend paid per share | — | — | — | — | 
                                                62.5
                                                
                                             | — | — | — | — | 
                                                27.0
                                                
                                             | — | — | — | 
                                                30.5
                                                
                                             | — | — | — | — | 
                                                26.5
                                                
                                             | — | — | 
                                                16.0
                                                
                                             | — | — | — | 
| Interim dividend paid per share | — | — | — | — |  | — | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — |  | — | — | — | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                57.46
                                                
                                             | — | 
                                                202.20
                                                
                                             | — | — | 
                                                47.31
                                                
                                             | — | — | 
                                                133.51
                                                
                                             | 
                                                117.67
                                                
                                             | 
                                                151.41
                                                
                                             | — | — | — | 
                                                29.91
                                                
                                             | 
                                                132.36
                                                
                                             | — | 
                                                38.33
                                                
                                             | — | 
                                                78.00
                                                
                                             | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | 
                                                0.315
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.233
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.246
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.302
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.294
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.256
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.288
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.241
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.282
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.264
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                0.078
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.140
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.066
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.102
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.177
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.126
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.049
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.121
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.064
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.077
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                23.60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                6.71
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                19.53
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                6.92
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.62
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5.92
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                31.99
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                18.84
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                9.26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | 
                                                1.088
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.571
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.259
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.886
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.417
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | 
                                                4,621,942,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,527,484,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,826,568,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                2,046,058,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,400,597,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | 
                                                -1,233,804,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -1,029,536,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,271,468,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,022,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,221,691,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | 
                                                -1,426,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -114,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,099,397,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,674,638,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -333,007,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | 
                                                29,148,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                27,169,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                25,496,356,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                22,848,737,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                20,138,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                1,526
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,100
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,545
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                135
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                174
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4,480
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                135
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                139
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,290
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                4,052
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                152
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,132
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                165
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4,165
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                164
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                2,207
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,095
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                333
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                71
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                3,729
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                3,739
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                3,857
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,103
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                4,383
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | 
                                                0.736
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.496
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.470
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.484
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.358
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | — | 
                                                1.962
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.388
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.312
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.286
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.905
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |