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 | 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 | 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 | — | — | — | — | 
                                                96,235,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                105,824,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                96,149,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                105,709,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                91,191,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                101,027,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                91,755,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                101,257,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                87,712,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                96,238,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Ordinary profit (loss) | — | — | — | — | 
                                                7,361,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,412,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,008,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,342,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,972,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,598,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,225,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,734,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,939,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,260,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Profit (loss) attributable to owners of parent | — | — | — | — | — | — | — | 
                                                5,784,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                5,621,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,132,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                6,588,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,211,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Comprehensive income | — | — | — | — | — | — | — | 
                                                7,005,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                5,564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,211,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                7,293,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                4,129,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets | — | — | — | — | — | — | — | — | 
                                                84,284,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                77,279,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                73,673,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                79,704,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                76,712,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                70,730,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                74,767,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                69,126,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                71,032,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                66,648,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Total assets | — | — | — | — | — | — | — | — | 
                                                102,701,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                93,968,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                90,390,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                98,188,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                94,371,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                86,884,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                94,028,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                86,336,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                82,798,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                76,464,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets per share | — | — | — | — | — | — | — | — | 
                                                2,410.12
                                                
                                             | 
                                                2,254.48
                                                
                                             | — | — | 
                                                2,153.95
                                                
                                             | 
                                                2,283.42
                                                
                                             | — | — | — | 
                                                2,177.99
                                                
                                             | 
                                                2,046.20
                                                
                                             | 
                                                2,086.85
                                                
                                             | — | — | 
                                                1,967.11
                                                
                                             | — | 
                                                1,921.50
                                                
                                             | — | 
                                                1,833.85
                                                
                                             | 
| Basic earnings (loss) per share | — | — | — | — | 
                                                152.61
                                                
                                             | — | — | 
                                                169.42
                                                
                                             | — | — | — | 
                                                166.92
                                                
                                             | — | — | 
                                                164.34
                                                
                                             | 
                                                140.09
                                                
                                             | 
                                                146.55
                                                
                                             | — | — | — | 
                                                160.69
                                                
                                             | 
                                                186.58
                                                
                                             | — | 
                                                115.12
                                                
                                             | — | 
                                                114.61
                                                
                                             | — | 
| Diluted earnings per share | — | — | — | — | 
                                                150.71
                                                
                                             | — | — | 
                                                167.31
                                                
                                             | — | — | — |  | — | — |  |  |  | — | — | — |  |  | — |  | — |  | — | 
| Equity-to-asset ratio | — | — | — | — | — | — | — | — | 
                                                0.801
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.819
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.814
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.794
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.798
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.814
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.780
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.801
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.843
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.872
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Rate of return on equity | — | — | — | — | 
                                                0.069
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.072
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.079
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.073
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.070
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.069
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.084
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.092
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.064
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.061
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Price-earnings ratio | — | — | — | — | 
                                                13.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                12.4
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                11.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                11.8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                11.6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                10.0
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                11.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | — | — | — | — | — | — | 
                                                5,377,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                7,121,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                5,007,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                8,855,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                8,583,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | — | — | — | — | — | — | 
                                                -1,309,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -304,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -1,032,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                -483,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -538,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | — | — | — | — | — | — | 
                                                -2,726,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | — | — | 
                                                -2,860,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -3,424,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                1,884,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                -10,647,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | — | — | — | — | — | — | — | 
                                                54,187,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                52,639,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                48,581,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                47,870,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | — | 
                                                37,549,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Number of employees | 
                                                270
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                302
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                248
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                302
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                491
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                324
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,365
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                820
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                248
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                825
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,387
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                1,478
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                817
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                1,486
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                842
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                1,500
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                822
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Average number of temporary employees | 
                                                15
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                60
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                371
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                21
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                460
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                83
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                8
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                98
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                517
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                598
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                111
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                598
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                121
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                556
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                134
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             |