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 | ||
| Buildings and structures | — | — | 
| Buildings and structures, net | 
                                                8,659,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,925,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Own-used assets | ||
| Machinery, equipment and vehicles | — | — | 
| Machinery, equipment and vehicles, net | 
                                                4,416,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,026,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Land | 
                                                11,124,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                11,145,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Leased assets | — | — | 
| Leased assets, net | 
                                                156,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                188,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Construction in progress | 
                                                5,450,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                769,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | — | — | 
| Other, net | 
                                                793,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                676,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Property, plant and equipment | 
                                                30,600,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,731,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | 
                                                1,246,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,246,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Intangible assets | ||
| Other intangible assets | ||
| Investments and other assets | ||
| Investment securities | 
                                                8,889,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                9,753,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax assets | 
                                                86,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                76,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                753,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                712,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -56,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -58,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit asset | 
                                                3,130,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,773,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Investments and other assets | 
                                                18,129,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                18,595,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Non-current assets | 
                                                49,977,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                45,529,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | ||
| Cash and deposits | 
                                                18,979,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                25,745,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Costs on construction contracts in progress | 
                                                764,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                142,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Merchandise and finished goods | 
                                                1,254,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,431,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Raw materials and supplies | 
                                                1,202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,317,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,070,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                720,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Allowance for doubtful accounts | 
                                                -6,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -57,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current assets | 
                                                40,478,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                49,564,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Assets | 
                                                90,456,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                95,094,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | ||
| Non-current liabilities | 
                                                2,307,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,392,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Long-term borrowings | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                55,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Lease liabilities | 
                                                92,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                105,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retirement benefit liability | 
                                                75,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Asset retirement obligations | 
                                                135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                135,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Deferred tax liabilities | 
                                                1,954,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,048,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current liabilities | 
                                                13,917,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                17,865,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Short-term borrowings | 
                                                1,300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,300,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Notes and accounts payable - trade | 
                                                6,782,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                8,664,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Accounts payable - other | 
                                                1,171,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,020,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | 
                                                16,225,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                20,258,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Shareholders' equity | 
                                                70,057,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                70,140,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Share capital | 
                                                2,919,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                2,919,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Capital surplus | 
                                                4,054,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,028,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Retained earnings | 
                                                66,062,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                66,200,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Treasury shares | 
                                                -2,979,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                -3,008,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation and translation adjustments | 
                                                4,173,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                4,695,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Valuation difference on available-for-sale securities | 
                                                2,970,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                3,565,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Foreign currency translation adjustment | 
                                                329,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                202,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | 
                                                74,231,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                74,836,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities and net assets | 
                                                90,456,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                95,094,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Liabilities | ||
| Non-current liabilities | ||
| Current liabilities | ||
| Income taxes payable | 
                                                397,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,123,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Current portion of long-term borrowings | 
                                                
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Provisions | ||
| Provision for bonuses | 
                                                928,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,060,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Other | 
                                                1,332,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                1,510,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
| Net assets | ||
| Shareholders' equity | ||
| Valuation and translation adjustments | ||
| Remeasurements of defined benefit plans | 
                                                873,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             | 
                                                927,000,000
                                                
                                                    
                                                        JPY
                                                    
                                                
                                             |