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 | 
                                                709,694,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                432,511,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                1,531,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,157,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -141,716,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -83,658,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                569,509,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                350,009,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | ||||||
| Purchase of property, plant and equipment | 
                                                -134,633,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -225,760,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -967,863,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -209,949,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                2,440,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                28,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | ||||||
| Dividends paid | 
                                                -141,590,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -141,520,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                -143,209,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -143,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                -541,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -2,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                3,557,832,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,099,395,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                3,714,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,717,088,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |