Consolidated Statement Of Cash Flows
| Concept | 2024-04-01 to 2025-03-31 | As at 2025-03-31 | 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 | 
                                                1,309,490,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,272,893,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Depreciation | 
                                                55,674,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                32,982,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Increase (decrease) in provision for retirement benefits | 
                                                26,909,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                20,535,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest expenses | 
                                                145,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                140,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Increase (decrease) in provision for bonuses | 
                                                22,478,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,831,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Decrease (increase) in trade receivables | 
                                                -65,196,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -203,993,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Subtotal | 
                                                1,550,385,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,126,567,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Income taxes paid | 
                                                -447,721,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -354,255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Decrease (increase) in inventories | 
                                                -3,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                2,440,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Increase (decrease) in trade payables | 
                                                12,055,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -61,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | 
                                                1,104,251,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                772,202,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | 
                                                59,077,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                119,208,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest paid | 
                                                -141,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -141,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from investing activities | |||||
| Purchase of property, plant and equipment | 
                                                -5,213,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -18,362,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | 
                                                -88,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -91,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from financing activities | |||||
| Proceeds from issuance of shares | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Purchase of treasury shares | 
                                                -115,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Dividends paid | 
                                                -180,407,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -98,563,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | 
                                                -195,830,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -110,935,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Repayments of lease liabilities | 
                                                -15,306,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -13,842,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                820,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                569,444,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | — | 
                                                3,478,664,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,658,578,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,001,899,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |