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 | 
|---|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | |||||||
| Statement of cash flows | |||||||
| Cash flows from operating activities | |||||||
| Profit (loss) before income taxes | 
                                                3,411,631,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,462,925,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,928,655,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                -15,049,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Depreciation | — | — | 
                                                576,234,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                544,340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Amortization of goodwill | — | — | 
                                                95,075,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                91,733,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in allowance for doubtful accounts | — | — | 
                                                -3,798,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,334,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividend income | — | — | 
                                                -265,538,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -182,111,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest expenses | — | — | 
                                                6,605,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Foreign exchange losses (gains) | — | — | 
                                                -20,462,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -295,096,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in provision for bonuses | — | — | 
                                                146,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                59,303,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in retirement benefit liability | — | — | 
                                                -32,859,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -549,163,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in trade receivables | — | — | 
                                                86,944,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,448,481,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Subtotal | — | — | 
                                                8,380,860,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,719,242,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in inventories | — | — | 
                                                35,670,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -241,206,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes paid | — | — | 
                                                -2,631,620,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,616,673,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                6,001,678,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,281,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in trade payables | — | — | 
                                                -156,266,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                145,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -196,152,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                544,708,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Loss (gain) on sale of non-current assets | — | — | 
                                                -340,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividends received | — | — | 
                                                259,044,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                182,664,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest paid | — | — | 
                                                -6,605,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,239,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from investing activities | |||||||
| Proceeds from withdrawal of time deposits | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                213,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of property, plant and equipment | — | — | 
                                                -1,733,589,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -384,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -1,883,886,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -194,810,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from collection of loans receivable | — | — | 
                                                6,050,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                13,967,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                3,233,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,858,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from financing activities | |||||||
| Purchase of treasury shares | — | — | 
                                                -217,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividends paid | — | — | 
                                                -1,407,477,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,059,922,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from long-term borrowings | — | — | 
                                                1,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repayments of long-term borrowings | — | — | 
                                                -253,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -150,418,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -700,473,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -213,343,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repayments of lease liabilities | — | — | 
                                                -39,306,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,002,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | — | 
                                                -142,640,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                402,523,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | — | 
                                                3,274,678,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,276,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | — | 
                                                12,647,928,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                9,373,250,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                6,096,888,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |