Consolidated Statement Of Cash Flows
| Concept | As at 2023-09-30 | 2023-04-01 to 2023-09-30 | As at 2023-03-31 | As at 2022-09-30 | 2022-04-01 to 2022-09-30 | As at 2022-03-31 | 
|---|---|---|---|---|---|---|
| Consolidated statement of cash flows | ||||||
| Statement of cash flows | ||||||
| Cash flows from operating activities | ||||||
| Subtotal | — | 
                                                1,629,457,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                1,422,508,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest and dividends received | — | 
                                                30,883,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                24,540,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Interest paid | — | 
                                                -2,958,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -2,603,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Income taxes paid | — | 
                                                -520,059,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -533,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) operating activities | — | 
                                                1,137,322,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                910,988,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from investing activities | ||||||
| Purchase of property, plant and equipment | — | 
                                                -61,757,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -121,136,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Purchase of investment securities | — | 
                                                -664,643,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -609,731,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) investing activities | — | 
                                                -652,217,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -638,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | — | 
                                                -25,816,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -7,604,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash flows from financing activities | ||||||
| Proceeds from short-term borrowings | — | 
                                                600,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                400,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Repayments of short-term borrowings | — | 
                                                -500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -500,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Dividends paid | — | 
                                                -219,312,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -155,012,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net cash provided by (used in) financing activities | — | 
                                                -149,273,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -275,484,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Other, net | — | 
                                                -29,961,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                -20,472,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Effect of exchange rate change on cash and cash equivalents | — | 
                                                18,451,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                49,363,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Net increase (decrease) in cash and cash equivalents | — | 
                                                354,282,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | — | 
                                                46,394,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
| Cash and cash equivalents | 
                                                8,376,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                8,022,014,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                7,958,141,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | — | 
                                                7,911,746,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |