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 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 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 | — | — | — | — | — | 
                                                12,764,689,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,986,882,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10,818,427,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                11,039,908,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,164,932,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,381,548,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,190,317,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,404,895,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,472,876,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,742,940,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | 
                                                1,054,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,075,002,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                507,554,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                512,726,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                224,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                236,070,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -116,469,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -58,026,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,354,673,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,446,612,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | 
                                                672,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                510,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,782,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                18,191,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                760,890,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | — | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,038,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | — | 
                                                13,510,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | 
                                                13,510,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                13,950,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                13,950,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                13,950,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | 
                                                9,353,925,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,951,845,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,798,132,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,180,243,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                9,357,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,056,594,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,330,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                9,061,156,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                9,372,650,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                9,145,097,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | 
                                                13,796,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,554,621,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,134,261,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,354,902,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,250,462,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,946,064,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,507,396,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                14,230,264,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,699,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                13,632,934,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | 
                                                715.77
                                                
                                             | — | — | 
                                                685.01
                                                
                                             | — | — | 
                                                673.26
                                                
                                             | 
                                                702.50
                                                
                                             | — | — | — | 
                                                670.90
                                                
                                             | 
                                                649.31
                                                
                                             | 
                                                668.97
                                                
                                             | — | — | 
                                                649.64
                                                
                                             | — | 
                                                671.97
                                                
                                             | — | 
                                                655.66
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | 
                                                45
                                                
                                             | — | — | — | — | — | — | 
                                                30
                                                
                                             | — | — | — | 
                                                5
                                                
                                             | — | — | — | — |  | — | — | 
                                                13
                                                
                                             | — | — | — | 
| Interim dividend paid per share | — | — | — | — | — | 
                                                15
                                                
                                             | — | — | — | — | — | — | 
                                                5
                                                
                                             | — | — | — |  | — | — | — | — |  | — | — | 
                                                5
                                                
                                             | — | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | 
                                                51.42
                                                
                                             | 
                                                52.76
                                                
                                             | — | — | — | — | — | 
                                                37.22
                                                
                                             | — | — | 
                                                37.26
                                                
                                             | 
                                                0.12
                                                
                                             | 
                                                0.81
                                                
                                             | — | — | — | 
                                                1.30
                                                
                                             | 
                                                -3.29
                                                
                                             | — | 
                                                54.55
                                                
                                             | — | 
                                                35.75
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — |  |  | — | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | 
                                                0.678
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.660
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.670
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.687
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.657
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.649
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.643
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.637
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.638
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.671
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | 
                                                0.076
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.074
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.057
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.055
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.000
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.001
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.002
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                -0.005
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.086
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.054
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | 
                                                17.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                16.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                21.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                21.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4,218.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                658.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                420.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                6.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                10.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | 
                                                0.875
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                0.806
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                39.154
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.238
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | 
                                                1,175,327,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                710,955,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                459,539,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,472,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,717,950,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | 
                                                -754,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -422,843,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -313,532,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -792,453,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,248,176,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | 
                                                -806,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -1,034,278,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -59,027,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                772,671,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -457,170,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | 
                                                3,848,921,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                4,230,689,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,972,709,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,883,705,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                3,422,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                129
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                379
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                638
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                395
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                48
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                590
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                139
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                613
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                662
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                679
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                629
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                738
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                688
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                748
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                352
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | — | 
                                                1.353
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.171
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.768
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.774
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.510
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | — | — | — | 
                                                1.863
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1.318
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.246
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.222
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.859
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |