Consolidated Balance Sheet
| Concept | As at 2024-09-30 | As at 2024-03-31 | 
|---|---|---|
| Consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Non-current assets | ||
| Property, plant and equipment | 
                                                2,869,308,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,653,584,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | — | — | 
| Buildings and structures, net | 
                                                2,174,071,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,968,127,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Own-used assets | ||
| Other | 
                                                695,236,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                685,456,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Intangible assets | 
                                                18,193,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,470,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Allowance for doubtful accounts | 
                                                -135,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -135,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                995,827,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,021,144,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                3,883,330,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,678,199,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | ||
| Cash and deposits | 
                                                9,172,823,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,897,144,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accounts receivable - trade | 
                                                440,388,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                492,885,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                204,647,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                187,548,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                390,509,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                316,308,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                10,208,369,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,893,887,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                14,091,699,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,572,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Notes and accounts payable - trade | 
                                                628,085,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,258,434,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Income taxes payable | 
                                                474,864,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                633,838,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current portion of long-term borrowings | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                10,448,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,457,092,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,036,161,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                2,560,041,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,938,882,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Provision for retirement benefits for directors (and other officers) | 
                                                555,430,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                542,710,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                200,126,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                188,380,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                755,556,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                731,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                3,315,598,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,669,973,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | ||
| Shareholders' equity | 
                                                10,773,806,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,899,346,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share capital | 
                                                361,315,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                361,315,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                389,761,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                389,420,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                10,424,860,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,649,596,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -402,130,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -500,985,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                2,294,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,767,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation difference on available-for-sale securities | 
                                                2,294,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,767,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                10,776,101,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,902,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                14,091,699,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,572,086,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Valuation and translation adjustments |