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 | 
                                                2,084,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,628,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,273,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                2,042,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Depreciation | — | — | 
                                                3,145,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,795,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Impairment losses | — | — | 
                                                53,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in allowance for doubtful accounts | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividend income | — | — | 
                                                -51,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -34,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest expenses | — | — | 
                                                39,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                37,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in retirement benefit liability | — | — | 
                                                -1,989,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                51,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in provision for bonuses | — | — | 
                                                43,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                12,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Share of loss (profit) of entities accounted for using equity method | — | — | 
                                                31,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -39,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in trade receivables | — | — | 
                                                161,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -510,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Subtotal | — | — | 
                                                4,029,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,088,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Decrease (increase) in inventories | — | — | 
                                                -188,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -546,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Income taxes paid | — | — | 
                                                -352,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -898,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) operating activities | — | — | 
                                                3,690,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,187,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Increase (decrease) in trade payables | — | — | 
                                                -301,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -60,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                80,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -89,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest and dividends received | — | — | 
                                                51,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                34,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Interest paid | — | — | 
                                                -37,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -37,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from investing activities | |||||||
| Payments into time deposits | — | — | 
                                                -287,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -581,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from withdrawal of time deposits | — | — | 
                                                287,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                581,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of property, plant and equipment | — | — | 
                                                -1,295,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,546,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of property, plant and equipment | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                81,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) investing activities | — | — | 
                                                -1,695,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,692,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Purchase of investment securities | — | — | 
                                                -5,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -5,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Proceeds from sale of investment securities | — | — | 
                                                61,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Other, net | — | — | 
                                                -9,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -2,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash flows from financing activities | |||||||
| Purchase of treasury shares | — | — | 
                                                0
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -448,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Dividends paid | — | — | 
                                                -711,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -721,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net cash provided by (used in) financing activities | — | — | 
                                                -763,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,225,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Repayments of lease liabilities | — | — | 
                                                -51,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -55,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Effect of exchange rate change on cash and cash equivalents | — | — | 
                                                25,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                27,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Net increase (decrease) in cash and cash equivalents | — | — | 
                                                1,257,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -1,702,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | — | 
| Cash and cash equivalents | — | 
                                                14,307,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                13,049,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                14,752,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |