Consolidated Statement Of Cash Flows
| Concept | 2024-04-01 to 2024-09-30 | As at 2024-09-30 | As at 2024-03-31 | 2023-04-01 to 2023-09-30 | As at 2023-09-30 | As at 2023-03-31 | 
|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | ||||||
| Statement of cash flows | ||||||
| Cash flows from operating activities | ||||||
| Subtotal | 
                                                738,996,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -424,569,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                2,761,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                4,225,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -216,499,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -4,439,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                528,650,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -412,249,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | ||||||
| Purchase of property, plant and equipment | 
                                                -103,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -14,064,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -179,285,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -86,236,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of investment securities | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | ||||||
| Purchase of treasury shares | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -65,429,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | 
                                                -104,856,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -104,800,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -104,856,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -169,903,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                244,508,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -668,389,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                2,084,091,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,839,582,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,331,663,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,052,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |