Consolidated 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 | 
|---|---|---|---|---|---|
| Consolidated statement of cash flows | |||||
| Statement of cash flows | |||||
| Cash flows from operating activities | |||||
| Subtotal | — | 
                                                129,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -438,043,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | — | 
                                                559,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                149,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | — | 
                                                -41,978,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -40,894,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | — | 
                                                123,398,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                642,825,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | — | 
                                                -43,523,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,772,365,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from sale of property, plant and equipment | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,327,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -45,238,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,771,377,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                510,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | |||||
| Purchase of treasury shares | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from long-term borrowings | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | — | 
                                                -233,317,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -174,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -263,399,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                609,538,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | 
                                                -1,254,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                15,211,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | 
                                                -186,494,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -503,801,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | 
                                                1,308,830,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,495,324,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,999,126,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |