Key Financial Data Of Group
| Concept | 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 2023-03-31 | 2022-04-01 to 2023-03-31 | 2021-04-01 to 2022-03-31 | As at 2022-03-31 | 2020-04-01 to 2021-03-31 | As at 2021-03-31 | As at 2020-03-31 | 2019-04-01 to 2020-03-31 | 
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Key financial data of group | |||||||||||||
| Business results of group | |||||||||||||
| Net sales | — | — | — | 
                                                7,071,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                6,584,391,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,467,394,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,417,567,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                9,802,723,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Ordinary profit (loss) | — | — | — | 
                                                467,571,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                430,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                480,209,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                574,001,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                589,570,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | — | 
                                                10,853,149,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                10,365,732,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                10,175,112,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                10,180,584,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,636,161,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Total assets | — | 
                                                14,416,338,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                13,480,011,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,626,980,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,144,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,035,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net assets per share | — | 
                                                825.51
                                                
                                             | — | — | — | 
                                                788.43
                                                
                                             | — | — | 
                                                773.93
                                                
                                             | — | 
                                                744.34
                                                
                                             | 
                                                732.93
                                                
                                             | — | 
| Basic earnings (loss) per share | — | — | — | 
                                                25.68
                                                
                                             | — | — | 
                                                23.70
                                                
                                             | 
                                                23.57
                                                
                                             | — | 
                                                31.19
                                                
                                             | — | — | 
                                                29.04
                                                
                                             | 
| Diluted earnings per share | — | — | — |  | — | — |  |  | — |  | — | — |  | 
| Equity-to-asset ratio | — | 
                                                0.753
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | — | 
                                                0.769
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.747
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.720
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.687
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Rate of return on equity | — | — | — | 
                                                0.032
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.030
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                0.030
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                0.041
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                0.040
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Price-earnings ratio | — | — | — | 
                                                28.5
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                29.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                29.7
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                27.1
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                22.2
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
| Net cash provided by (used in) operating activities | — | — | — | 
                                                414,785,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                740,075,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                388,024,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                647,255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                694,483,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) investing activities | — | — | — | 
                                                -42,315,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -352,052,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -322,101,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                136,798,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -556,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net cash provided by (used in) financing activities | — | — | — | 
                                                -186,571,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -191,824,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -499,943,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -196,107,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -174,282,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Cash and cash equivalents | — | 
                                                2,588,332,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
                                                2,402,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,206,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,640,255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,052,309,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Number of employees | 
                                                
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                194
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                6
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                188
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                199
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                209
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                211
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                212
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
| Average number of temporary employees | — | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                23
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | — | 
                                                25
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — | 
                                                20
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | 
                                                28
                                                
                                                    
                                                        xbrli:pure
                                                    
                                                
                                             | — |