| Mar 31,
2020 | Mar 31,
2021 | Mar 31,
2022 | Mar 31,
2023 |
|---|
| Non-current assets | - | 430,728 | 422,510 | 444,509 |
|---|
| Electric utility plant and equipment | - | 385,783 | 381,084 | 378,105 |
|---|
| Hydroelectric power production facilities | - | 374,436 | 370,101 | 368,734 |
|---|
| Renewable power production facilities | - | 11,246 | 10,670 | 9,106 |
|---|
| Other electric utility plant and equipment | - | 100 | 313 | 264 |
|---|
| Other non-current assets | - | 1 | 1 | 14,560 |
|---|
| Construction in progress | - | 12,306 | 9,488 | 14,029 |
|---|
| Construction and retirement in progress | - | 16,312 | 14,708 | 19,148 |
|---|
| Investments and other assets | - | 32,636 | 31,934 | 52,372 |
|---|
| Long-term investments | - | 740 | 697 | 841 |
|---|
| Retirement benefit asset | - | 6,335 | 6,225 | 5,550 |
|---|
| Deferred tax assets | - | 13,350 | 11,124 | 10,182 |
|---|
| Other | - | 26,525 | 27,765 | 30,947 |
|---|
| Allowance for doubtful accounts | - | - | - | - |
|---|
| Current assets | 8 | 88,537 | 110,262 | 156,997 |
|---|
| Cash and deposits | 8 | 1,000 | 1,000 | 1,000 |
|---|
| Notes and accounts receivable - trade, and contract assets | - | - | 11,667 | 12,483 |
|---|
| Inventories | - | 868 | 539 | 638 |
|---|
| Short-term receivables from subsidiaries and associates | - | 70,008 | 94,814 | 133,393 |
|---|
| Other | - | 3,218 | 3,979 | 13,202 |
|---|
| Allowance for doubtful accounts | - | -4 | - | - |
|---|
| Assets | 8 | 519,265 | 532,773 | 601,506 |
|---|
| Non-current liabilities | - | 42,744 | 77,238 | 101,635 |
|---|
| Bonds payable | - | - | 40,000 | 70,000 |
|---|
| Long-term borrowings | - | 26,228 | 21,878 | 18,031 |
|---|
| Retirement benefit liability | - | 13,340 | 13,028 | 12,831 |
|---|
| Other | - | 5,664 | 4,477 | 2,632 |
|---|
| Current liabilities | - | 123,146 | 106,130 | 145,596 |
|---|
| Current portion of non-current liabilities | - | 8,450 | 4,779 | 9,279 |
|---|
| Short-term borrowings | - | 67,840 | 75,174 | 103,410 |
|---|
| Notes and accounts payable - trade | - | 900 | 1,169 | 1,412 |
|---|
| Accrued taxes | - | 9,262 | 3,344 | 4,021 |
|---|
| Other | - | 27,831 | 15,186 | 18,774 |
|---|
| Liabilities | - | 165,890 | 183,369 | 247,231 |
|---|
| Shareholders' equity | 8 | 353,375 | 349,403 | 354,274 |
|---|
| Share capital | 5 | 1,000 | 1,000 | 1,000 |
|---|
| Capital surplus | 5 | 305,949 | 305,949 | 305,949 |
|---|
| Retained earnings | -1 | 46,426 | 42,454 | 47,325 |
|---|
| Valuation and translation adjustments | - | 588 | 914 | 2,173 |
|---|
| Foreign currency translation adjustment | - | 97 | 738 | 2,719 |
|---|
| Remeasurements of defined benefit plans | - | 490 | 176 | -545 |
|---|
| Non-controlling interests | - | 8,311 | 8,917 | 9,420 |
|---|
| Net assets | 8 | 353,375 | 349,403 | 354,274 |
|---|
| Liabilities and net assets | 8 | 519,265 | 532,773 | 601,506 |
|---|