Key Financial Data Of Reporting Company
| Concept | As at 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 | 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 | 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 | — | — | 
                                                156,365,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                307,699,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                163,507,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                329,389,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                146,897,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                284,096,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                121,103,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                216,233,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                147,665,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                329,360,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | 
                                                9,421,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                14,476,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                10,060,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                12,437,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,089,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,274,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,193,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,656,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,442,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,685,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) | — | — | 
                                                6,184,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                7,552,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                5,950,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                95,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,658,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share capital | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                6,800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                6,800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                6,800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total number of issued shares | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                25,303,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | 
                                                25,303,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | — | — | 
                                                25,303,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                25,303,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | — | — | — | 
                                                25,303,000
                                                
                                                    
                                                        xbrli:shares
                                                    
                                                
                                             | 
| Net assets | — | — | — | — | — | — | 
                                                82,097,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                62,011,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                57,601,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                72,158,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                65,096,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                52,541,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                58,831,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                47,979,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                57,279,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                48,468,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | 
                                                143,350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                95,351,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                86,639,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                143,200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                134,121,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                84,471,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                110,591,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                77,892,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                114,400,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                74,911,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | 
                                                3,330.03
                                                
                                             | — | — | — | — | — | 
                                                2,516.55
                                                
                                             | — | 
                                                2,340.85
                                                
                                             | 
                                                2,932.46
                                                
                                             | — | — | — | 
                                                2,643.55
                                                
                                             | 
                                                2,135.07
                                                
                                             | 
                                                2,390.06
                                                
                                             | — | — | 
                                                1,950.38
                                                
                                             | — | 
                                                2,328.79
                                                
                                             | — | 
                                                1,973.79
                                                
                                             | 
| Dividend paid per share | — | — | 
                                                118.00
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                105.00
                                                
                                             | — | — | — | 
                                                84.00
                                                
                                             | — | — | — | — | 
                                                37.00
                                                
                                             | — | — | 
                                                63.00
                                                
                                             | — | — | — | 
| Interim dividend paid per share | — | — | 
                                                58.00
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                50.00
                                                
                                             | — | — | — | 
                                                42.00
                                                
                                             | — | — | — | — | 
                                                14.00
                                                
                                             | — | — | 
                                                31.00
                                                
                                             | — | — | — | 
| Basic earnings (loss) per share | — | — | 
                                                251.16
                                                
                                             | — | — | 
                                                390.87
                                                
                                             | — | — | — | — | — | — | — | 
                                                306.91
                                                
                                             | — | — | 
                                                330.16
                                                
                                             | 
                                                241.83
                                                
                                             | 
                                                276.82
                                                
                                             | — | — | — | 
                                                3.87
                                                
                                             | 
                                                50.73
                                                
                                             | — | 
                                                189.72
                                                
                                             | — | 
                                                248.46
                                                
                                             | — | 
| Diluted earnings per share | — | — |  | — | — |  | — | — | — | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | 
                                                0.572
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                0.650
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.665
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.504
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.485
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.622
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.532
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.616
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.500
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.647
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | 
                                                0.103
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.125
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                0.137
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.118
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.118
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.002
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.022
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.099
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.110
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | 
                                                13.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                8.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                8.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                7.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                7.3
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                435.9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                33.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                8.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                6.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Payout ratio | — | — | 
                                                0.470
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                0.342
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.347
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                9.571
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.332
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | 
                                                9,693,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                9,596,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -2,330,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                5,889,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,857,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | 
                                                -2,706,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                -261,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                197,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -357,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | 
                                                -5,381,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | — | — | 
                                                -3,099,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -4,015,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -887,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -1,899,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | 
                                                21,088,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | — | 
                                                18,860,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                12,024,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                17,601,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                12,988,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                137
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                86
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                366
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,304
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                114
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                143
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                737
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                343
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                331
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,285
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,322
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                340
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                969
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                340
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,014
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                338
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                22
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                9
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                16
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                52
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                146
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                19
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                52
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                56
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                51
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                147
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                133
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                210
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                46
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                299
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                49
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Total shareholder return | — | — | — | — | — | — | — | — | — | — | — | — | 
                                                2.450
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1.798
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | — | 
                                                1.249
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.147
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1.028
                                                
                                                    
                                                        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
                                                    
                                                
                                             |