Consolidated Statement Of Cash Flows
| Concept | 2024-04-01 to 2024-09-30 | As at 2024-09-30 | As at 2024-03-31 | 2023-04-01 to 2023-09-30 | As at 2023-09-30 | As at 2023-03-31 | 
|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | ||||||
| Statement of cash flows | ||||||
| Cash flows from operating activities | ||||||
| Subtotal | 
                                                -64,811,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                60,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Interest paid | 
                                                -3,193,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -630,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Income taxes paid | 
                                                -31,926,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -36,512,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) operating activities | 
                                                -99,900,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -13,212,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from investing activities | ||||||
| Purchase of property, plant and equipment | 
                                                -80,766,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -75,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) investing activities | 
                                                -76,459,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -41,345,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Other, net | 
                                                -1,064,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -2,328,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash flows from financing activities | ||||||
| Proceeds from short-term borrowings | 
                                                24,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                22,500,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of short-term borrowings | 
                                                -38,349,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -38,335,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Proceeds from long-term borrowings | 
                                                100,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Repayments of long-term borrowings | 
                                                -31,255,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -20,455,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net cash provided by (used in) financing activities | 
                                                54,396,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -36,383,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Effect of exchange rate change on cash and cash equivalents | 
                                                -16,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Net increase (decrease) in cash and cash equivalents | 
                                                -121,981,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -90,941,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
| Cash and cash equivalents | — | 
                                                144,195,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                266,177,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                284,387,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                375,329,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |