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 | 
|---|---|---|---|---|---|---|---|
| Statement of cash flows | |||||||
| Statement of cash flows | |||||||
| Cash flows from operating activities | |||||||
| Profit (loss) before income taxes | 
                                                1,502,211,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,432,227,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,108,466,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                1,557,565,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Depreciation | — | — | 
                                                1,414,462,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,367,271,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in allowance for doubtful accounts | — | — | 
                                                -155,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -270,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividend income | — | — | 
                                                -510,418,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -473,980,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest expenses | — | — | 
                                                12,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,561,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in provision for bonuses | — | — | 
                                                12,190,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,141,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in trade receivables | — | — | 
                                                558,917,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                22,957,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in inventories | — | — | 
                                                -327,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                886,730,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Subtotal | — | — | 
                                                2,567,934,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,132,942,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in trade payables | — | — | 
                                                -272,027,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -804,702,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -6,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -29,167,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                2,366,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,007,843,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividends received | — | — | 
                                                509,735,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                474,455,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest paid | — | — | 
                                                -12,711,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -18,923,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from operating activities | |||||||
| Loss (gain) on sale of investment securities | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -8,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from operating activities | |||||||
| Loss (gain) on sale of securities | — | — | 
                                                -212,351,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -290,680,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from investing activities | |||||||
| Purchase of property, plant and equipment | — | — | 
                                                -1,549,280,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,134,005,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of property, plant and equipment | — | — | 
                                                1,327,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,038,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of investment securities | — | — | 
                                                -1,005,750,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -4,581,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -2,106,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -873,134,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of investment securities | — | — | 
                                                768,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                320,690,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Loan advances | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -6,490,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from collection of loans receivable | — | — | 
                                                250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from facilities maintenance and investing activities | |||||||
| Cash flows from financing activities | |||||||
| Purchase of treasury shares | — | — | 
                                                -217,007,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -210,224,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from long-term borrowings | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividends paid | — | — | 
                                                -473,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -481,336,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -1,600,661,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,341,768,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repayments of long-term borrowings | — | — | 
                                                -1,280,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,220,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | — | 
                                                14,967,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,630,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | — | 
                                                -1,325,634,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,428,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | — | 
                                                7,330,212,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                8,655,846,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,788,194,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |