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 | — | 
                                                1,394,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                561,152,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | — | 
                                                1,255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                147,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | — | 
                                                -46,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -66,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | — | 
                                                -16,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -8,764,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                1,322,194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                521,898,000
                                                
                                                    
                                                        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 | — | 
                                                -26,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -34,813,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of investment securities | — | 
                                                -1,100,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | — | 
                                                20,813,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,039,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||
| Net cash provided by (used in) investing activities | — | 
                                                -103,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -463,172,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Repayments of long-term borrowings | — | 
                                                -1,174,497,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -226,536,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -1,176,410,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -228,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | — | 
                                                -1,913,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,214,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | 
                                                42,531,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -164,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | 
                                                -22,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,979,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | 
                                                2,476,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,433,603,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,597,647,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |