Quarterly Consolidated Statement Of Cash Flows
| Concept | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | 2024-04-01 to 2025-03-31 | 2023-04-01 to 2024-03-31 | As at 2024-03-31 | 2023-04-01 to 2024-03-31 | As at 2023-03-31 | 
|---|---|---|---|---|---|---|---|
| Quarterly consolidated statement of cash flows | |||||||
| Statement of cash flows | |||||||
| Cash flows from operating activities | |||||||
| Profit (loss) before income taxes | 
                                                1,902,528,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,919,896,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,033,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                987,980,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Depreciation | — | — | 
                                                743,518,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                831,216,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividend income | — | — | 
                                                -41,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -37,743,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest expenses | — | — | 
                                                31,883,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                29,031,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Foreign exchange losses (gains) | — | — | 
                                                -10,432,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -115,684,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Loss (gain) on sale of property, plant and equipment | — | — | 
                                                -2,033,903,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -38,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in inventories | — | — | 
                                                14,349,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                57,923,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in trade payables | — | — | 
                                                -86,504,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -166,741,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                309,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,385,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Subtotal | — | — | 
                                                1,539,954,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,717,305,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividends received | — | — | 
                                                41,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,743,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest paid | — | — | 
                                                -31,429,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -27,929,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes paid | — | — | 
                                                -267,397,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -265,818,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                1,282,427,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,461,301,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from investing activities | |||||||
| Purchase of property, plant and equipment | — | — | 
                                                -536,337,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -532,322,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of property, plant and equipment | — | — | 
                                                2,197,728,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                43,320,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from collection of loans receivable | — | — | 
                                                3,120,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -3,647,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,235,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                1,660,863,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -490,376,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from financing activities | |||||||
| Proceeds from long-term borrowings | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                525,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repayments of long-term borrowings | — | — | 
                                                -1,135,669,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -378,210,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividends paid | — | — | 
                                                -153,605,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -153,906,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividends paid to non-controlling interests | — | — | 
                                                -58,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -883,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of shares of subsidiaries not resulting in change in scope of consolidation | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -77,550,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -90,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -1,296,009,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -90,331,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | — | 
                                                10,432,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                115,684,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | — | 
                                                1,657,714,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                996,277,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | — | 
                                                4,185,775,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,528,061,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,531,783,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |