Statement Of Cash Flows
| Concept | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | As at 2023-03-31 | 
|---|---|---|---|---|---|
| Statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | — | 
                                                2,570,833,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,588,074,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | — | 
                                                35,142,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                26,947,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | — | 
                                                -389,491,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,687,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | — | 
                                                -2,357,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,429,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                2,219,558,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,458,221,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from operating activities | |||||
| Cash flows from operating activities | |||||
| Cash flows from facilities maintenance and investing activities | |||||
| Purchase of property, plant and equipment | — | 
                                                -2,735,441,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,876,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from sale of property, plant and equipment | — | 
                                                100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,944,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from sale of investment securities | — | 
                                                147,737,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,787,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | — | 
                                                -4,281,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -15,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||
| Net cash provided by (used in) investing activities | — | 
                                                -2,669,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,828,269,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Purchase of treasury shares | — | 
                                                -111,597,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -348,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Dividends paid | — | 
                                                -301,827,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -211,128,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -1,231,446,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,347,091,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | — | 
                                                -808,802,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,124,123,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | 
                                                5,718,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,186,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | 
                                                -1,675,945,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,713,953,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | 
                                                6,335,572,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,011,517,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,725,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |