Consolidated Statement Of Cash Flows
| Concept | 2023-04-01 to 2023-09-30 | As at 2023-09-30 | As at 2023-03-31 | 2022-04-01 to 2022-09-30 | As at 2022-09-30 | As at 2022-03-31 | 
|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | ||||||
| Statement of cash flows | ||||||
| Cash flows from operating activities | ||||||
| Profit (loss) before income taxes | 
                                                75,536,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                87,761,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Depreciation | 
                                                67,437,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                66,863,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in allowance for doubtful accounts | 
                                                -255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                3,328,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividend income | 
                                                -932,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -698,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in provision for retirement benefits | 
                                                18,437,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,795,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest expenses | 
                                                1,117,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                642,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in provision for bonuses | 
                                                8,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                5,479,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Decrease (increase) in trade receivables | 
                                                355,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                350,411,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Subtotal | 
                                                228,650,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                304,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Decrease (increase) in inventories | 
                                                -19,543,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -25,253,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -39,759,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -76,166,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                207,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                228,034,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Increase (decrease) in trade payables | 
                                                -189,601,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -75,734,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest and dividends received | 
                                                932,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                698,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -1,039,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -697,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | ||||||
| Payments into time deposits | 
                                                -39,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -39,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from withdrawal of time deposits | 
                                                39,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                39,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Purchase of property, plant and equipment | 
                                                -122,278,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -53,264,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -172,300,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -89,599,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Loan advances | 
                                                -200,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -410,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from collection of loans receivable | 
                                                816,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                488,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | ||||||
| Dividends paid | 
                                                -60,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -54,511,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in short-term borrowings | 
                                                -380,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                40,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from long-term borrowings | 
                                                800,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | 
                                                -120,648,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -127,564,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                238,795,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -142,075,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                273,996,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -3,640,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                782,080,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                508,084,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                459,329,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                462,970,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |