Key Financial Data Of Reporting Company
| Concept | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 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 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of reporting company | ||||||||||||||||||||||||||||
| Business results of reporting company | ||||||||||||||||||||||||||||
| Net sales | — | — | — | — | — | 
                                                23,316,657,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                17,344,290,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                16,493,213,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,651,665,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                16,496,277,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                22,277,145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,960,508,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,598,576,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                14,932,880,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,938,449,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | 
                                                1,626,630,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                881,962,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                927,803,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,248,704,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                765,486,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,349,907,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                997,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,583,918,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                835,314,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,321,600,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | — | — | — | 
                                                800,190,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                720,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                566,252,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                720,498,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                588,480,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Share capital | — | — | — | — | — | — | 
                                                640,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                640,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                640,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                640,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                640,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | 
                                                4,450,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                4,450,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                4,450,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                4,450,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                4,450,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | 
                                                24,279,208,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                16,440,407,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                23,799,922,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,087,440,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                15,565,182,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                21,256,982,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                20,076,770,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,228,337,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                19,059,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                14,709,389,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | 
                                                33,384,523,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                24,203,331,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                33,316,898,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,377,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                23,442,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                30,351,778,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                29,396,063,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                23,310,204,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,826,063,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                22,310,510,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | 
                                                5,341.87
                                                
                                             | — | 
                                                3,744.96
                                                
                                             | — | — | — | — | — | — | — | 
                                                5,190.43
                                                
                                             | 
                                                3,848.49
                                                
                                             | — | 
                                                3,505.64
                                                
                                             | 
                                                4,614.07
                                                
                                             | — | — | — | 
                                                4,367.75
                                                
                                             | 
                                                3,429.78
                                                
                                             | 
                                                4,150.31
                                                
                                             | — | — | 
                                                3,312.90
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | 
                                                40.00
                                                
                                             | 
                                                40.00
                                                
                                             | — | — | — | 
                                                40.00
                                                
                                             | — | — | — | 
                                                40.00
                                                
                                             | — | — | — | — | 
                                                38.00
                                                
                                             | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — | — | — | — | 
                                                20.00
                                                
                                             | 
                                                20.00
                                                
                                             | — | — | — | 
                                                20.00
                                                
                                             | — | — | — | 
                                                19.00
                                                
                                             | — | — | — | — | 
                                                19.00
                                                
                                             | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | 
                                                297.41
                                                
                                             | — | — | — | — | — | 
                                                180.26
                                                
                                             | 
                                                162.33
                                                
                                             | 
                                                216.74
                                                
                                             | — | — | 
                                                127.53
                                                
                                             | — | — | 
                                                213.51
                                                
                                             | 
                                                162.27
                                                
                                             | 
                                                248.24
                                                
                                             | — | — | — | 
                                                132.54
                                                
                                             | 
                                                202.93
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — |  | — | — | — | — | — |  |  |  | — | — |  | — | — |  |  |  | — | — | — |  |  | — | 
| Equity-to-asset ratio | — | — | — | — | 
                                                0.702
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.679
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.692
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.673
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.664
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.675
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.660
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.653
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.662
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.659
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | 
                                                0.057
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.048
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.044
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.044
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.037
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.048
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.048
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.058
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.042
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.052
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | 
                                                6.23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                10.29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11.55
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.65
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                12.49
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.29
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6.07
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                14.03
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.2219
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.2464
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.3136
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.2465
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.2867
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | 
                                                1,974,016,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                992,482,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                773,831,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,839,513,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,509,618,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | 
                                                -2,287,115,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -700,431,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -773,192,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,164,755,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -868,349,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | 
                                                -326,972,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -240,994,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                -38,246,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -201,174,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -218,836,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | 
                                                7,579,493,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | 
                                                7,947,016,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,726,270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,593,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,123,104,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Number of employees | 
                                                228
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                665
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                365
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                490
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                116
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                664
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                364
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                354
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                660
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                657
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                358
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                670
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                364
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                125
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                91
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                85
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                125
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                94
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                107
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                133
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                147
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                117
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                145
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                117
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | 
                                                1.160
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                1.149
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.967
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.896
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.073
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | 
                                                2.134
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                2.168
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.534
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.450
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.421
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |