Quarterly Consolidated Balance Sheet
| Concept | As at 2023-12-31 | As at 2023-03-31 | 
|---|---|---|
| Quarterly consolidated balance sheet | ||
| Balance sheet | ||
| Assets | ||
| Current assets | ||
| Cash and deposits | 
                                                4,950,998,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,650,822,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Securities | 
                                                2,100,110,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,000,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Work in process | 
                                                1,148,612,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,172,087,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                555,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                577,884,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                239,536,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                261,820,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                15,645,547,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,677,976,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | ||
| Property, plant and equipment | 
                                                4,620,821,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,405,743,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | ||
| Buildings and structures | — | — | 
| Buildings and structures, net | 
                                                1,602,320,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,634,937,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Machinery, equipment and vehicles | — | — | 
| Machinery, equipment and vehicles, net | 
                                                1,601,633,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,625,544,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Land | 
                                                817,638,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                809,212,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | — | — | 
| Other, net | 
                                                599,229,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                336,049,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Intangible assets | 
                                                79,125,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                96,559,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                1,153,258,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,322,636,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | ||
| Investment securities | 
                                                849,859,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,009,772,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                304,099,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                313,564,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -700,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                5,853,205,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,824,939,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                21,498,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,502,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Current liabilities | ||
| Notes and accounts payable - trade | 
                                                1,947,529,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,180,871,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,045,491,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                691,514,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                5,504,959,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                5,115,209,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | ||
| Retirement benefit liability | 
                                                723,361,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                702,090,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                127,995,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                127,995,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                24,474,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                39,920,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current liabilities | 
                                                964,711,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                954,525,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                6,469,670,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,069,735,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Share capital | 
                                                3,779,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,779,113,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                3,498,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,498,197,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                7,214,640,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                6,771,418,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -48,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -48,447,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                14,443,503,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,000,282,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | ||
| Valuation difference on available-for-sale securities | 
                                                136,353,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                69,445,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                400,296,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                312,230,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Remeasurements of defined benefit plans | 
                                                48,928,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                51,221,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                585,578,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                432,897,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                15,029,082,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                14,433,179,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                21,498,753,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,502,915,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |