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 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 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 | — | — | — | — | — | — | — | — | 
                                                27,923,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                52,819,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                30,356,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                55,922,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,700,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                52,758,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                31,450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                52,874,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                37,391,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                59,886,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | — | — | — | — | 
                                                3,437,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,214,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                3,413,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,820,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,271,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,507,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,825,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,700,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,540,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | — | — | — | — | — | — | 
                                                6,232,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                2,739,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                1,990,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,605,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,025,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2,487,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,487,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                2,487,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,487,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,487,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                46,735,334
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                46,735,334
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                46,735,334
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                46,735,334
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                46,735,334
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | — | — | — | — | — | 
                                                82,419,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                66,003,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                59,954,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,946,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                74,365,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                58,114,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                72,266,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                57,734,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                69,792,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                54,640,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | — | — | — | — | 
                                                97,871,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                76,397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                75,911,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                97,148,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                96,249,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                75,156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                91,092,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                73,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                89,861,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                69,610,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | — | — | — | — | 
                                                1,814.81
                                                
                                             | — | 
                                                1,468.42
                                                
                                             | — | — | — | 
                                                1,333.84
                                                
                                             | 
                                                1,718.36
                                                
                                             | — | — | — | 
                                                1,639.95
                                                
                                             | 
                                                1,292.91
                                                
                                             | 
                                                1,594.65
                                                
                                             | — | — | 
                                                1,284.46
                                                
                                             | — | 
                                                1,541.50
                                                
                                             | — | 
                                                1,215.63
                                                
                                             | 
| Dividend paid per share | — | — | — | — | — | — | — | — | 
                                                78.00
                                                
                                             | — | — | — | — | — | — | — | 
                                                19.00
                                                
                                             | — | — | — | 
                                                19.00
                                                
                                             | — | — | — | — | 
                                                11.00
                                                
                                             | — | — | 
                                                16.00
                                                
                                             | — | — | — | 
| Interim dividend paid per share | — | — | — | — | — | — | — | — |  | — | — | — | — | — | — | — |  | — | — | — |  | — | — | — | — |  | — | — |  | — | — | — | 
| Basic earnings (loss) per share | — | — | — | — | — | — | — | — | 
                                                138.65
                                                
                                             | — | 
                                                89.47
                                                
                                             | — | — | — | — | — | 
                                                60.95
                                                
                                             | — | — | 
                                                69.72
                                                
                                             | 
                                                44.28
                                                
                                             | 
                                                68.27
                                                
                                             | — | — | — | 
                                                35.73
                                                
                                             | 
                                                18.20
                                                
                                             | — | 
                                                45.05
                                                
                                             | — | 
                                                39.33
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | — | — | — | — |  | — |  | — | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | — | — | — | — | 
                                                0.833
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.864
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.790
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.795
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.766
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.773
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.787
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.783
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.771
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.785
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | — | — | — | — | 
                                                0.099
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.051
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.046
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.042
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.034
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.042
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.029
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.012
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.037
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.025
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | — | — | — | — | 
                                                10.13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                15.69
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                11.65
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                10.18
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14.05
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9.11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                20.51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                40.27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11.56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                13.25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | — | — | — | — | — | — | 
                                                0.563
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.312
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.429
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.308
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.355
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | — | — | — | — | 
                                                6,087,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                4,655,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,137,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,424,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                3,689,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | — | — | — | — | 
                                                4,062,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -1,223,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,103,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -614,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | — | — | — | — | 
                                                -2,173,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                -1,341,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -983,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -1,052,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,248,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | — | — | — | — | 
                                                43,343,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                35,288,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                33,037,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                30,866,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                27,450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                129
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                147
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                167
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                43
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                129
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                390
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                119
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,474
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                532
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                852
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                47
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                576
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                864
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,582
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,599
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                871
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,571
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                880
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,632
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                890
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                57
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                10
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                123
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                55
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                17
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                33
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                154
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                170
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                34
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                176
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                41
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                201
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                52
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2.574
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.290
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.265
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.894
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total return on share price index | — | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                1.962
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.388
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.312
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.286
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.905
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |