Key Financial Data Of Group
| Concept | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | 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 | 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 group | ||||||||||||||||||||||||||
| Business results of group | ||||||||||||||||||||||||||
| Net sales | — | — | — | — | 
                                                104,440,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                140,732,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                96,125,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                126,696,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                85,280,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                110,120,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                83,920,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                109,650,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                91,240,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                117,141,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                7,397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,585,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                6,236,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,172,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,493,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,120,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,941,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,806,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,058,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,714,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | — | — | 
                                                7,004,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                5,230,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,724,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                4,795,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,763,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | — | — | 
                                                10,273,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                6,115,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,227,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                7,369,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,439,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | — | — | — | — | 
                                                53,437,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                40,099,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                35,388,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                45,492,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                41,669,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                32,901,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                38,591,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                30,603,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                32,291,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                26,025,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | 
                                                100,479,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                80,153,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                75,376,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                92,058,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                84,693,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                70,609,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                81,484,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                68,764,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                80,215,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                68,060,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | 
                                                1,299.26
                                                
                                             | — | 
                                                975.02
                                                
                                             | — | — | 
                                                861.81
                                                
                                             | 
                                                1,107.88
                                                
                                             | — | — | — | 
                                                1,016.52
                                                
                                             | 
                                                802.63
                                                
                                             | 
                                                942.29
                                                
                                             | — | — | 
                                                747.26
                                                
                                             | — | 
                                                789.14
                                                
                                             | — | 
                                                636.00
                                                
                                             | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                119.39
                                                
                                             | 
                                                170.36
                                                
                                             | — | — | — | — | 
                                                106.69
                                                
                                             | — | — | 
                                                127.43
                                                
                                             | 
                                                92.14
                                                
                                             | 
                                                115.27
                                                
                                             | — | — | — | 
                                                92.17
                                                
                                             | 
                                                117.10
                                                
                                             | — | 
                                                84.02
                                                
                                             | — | 
                                                116.48
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — |  |  | — | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | 
                                                0.532
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.500
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.469
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.494
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.492
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.466
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.474
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.445
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.403
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.382
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                0.130
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.142
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                0.128
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.120
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.119
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.118
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.133
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.135
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.138
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.156
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                27.05
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                18.96
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | — | 
                                                13.67
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                11.44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6.60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                10.50
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8.26
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                7.44
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                5.37
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | 
                                                9,939,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                4,758,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                11,010,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                5,242,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,971,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | 
                                                -437,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -5,032,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -5,127,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -2,265,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -3,194,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | 
                                                -6,016,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | — | 
                                                -2,649,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -3,296,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -3,795,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -4,574,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | 
                                                8,524,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | 
                                                4,938,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                7,660,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                4,880,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                5,699,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                533
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                334
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                347
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                185
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                2,614
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,335
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,065
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                945
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,045
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,505
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                2,419
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,019
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                2,087
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                1,000
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                2,003
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                959
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                14
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                27
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                12
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                13
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                30
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |