Statement Of Cash Flows
| Concept | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2023-03-31 | 
|---|---|---|---|---|---|
| Statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | 
                                                62,286,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                265,539,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest and dividends received | 
                                                19,544,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                15,341,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Income taxes paid | 
                                                -17,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,146,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest paid | 
                                                -2,562,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -167,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | 
                                                63,207,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                281,471,000
                                                
                                                    
                                                        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 | 
                                                -428,492,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -329,899,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Proceeds from sale of property, plant and equipment | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                116,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Purchase of investment securities | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -27,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Proceeds from sale of investment securities | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,485,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from investing activities | |||||
| Net cash provided by (used in) investing activities | 
                                                -515,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -360,377,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from financing activities | |||||
| Proceeds from borrowings | 
                                                350,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                250,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Repayments of borrowings | 
                                                -9,996,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -1,666,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Purchase of treasury shares | 
                                                -863,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Dividends paid | 
                                                -37,142,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -31,838,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                208,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                153,692,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | 
                                                -2,046,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                -244,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                74,787,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                793,253,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,037,268,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                962,481,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |