| Mar 31,
2018 | Mar 31,
2019 | Mar 31,
2020 | Mar 31,
2021 | Mar 31,
2022 | Mar 31,
2023 | Mar 31,
2024 |
|---|
| Cash and deposits | - | 2,991 | 2,007 | 1,251 | 3,276 | 2,710 | 2,053 |
|---|
| Accounts receivable - trade | - | - | - | 55 | 17 | 59 | 76 |
|---|
| Securities | - | - | - | - | - | - | 301 |
|---|
| Finished goods | - | - | - | 25 | 66 | 89 | 101 |
|---|
| Work in process | - | 217 | 290 | 258 | 706 | 850 | 1,013 |
|---|
| Raw materials and supplies | - | 64 | 16 | 110 | 2 | 2 | 3 |
|---|
| Prepaid expenses | - | 58 | 47 | 41 | 36 | 39 | 41 |
|---|
| Other | - | 3 | 41 | 71 | 72 | 43 | 43 |
|---|
| Current assets | - | 3,362 | 2,401 | 1,811 | 4,175 | 3,793 | 3,629 |
|---|
| Buildings | - | 20 | 20 | 21 | 21 | 21 | 20 |
|---|
| Accumulated depreciation | - | -8 | -10 | -11 | -13 | -14 | -14 |
|---|
| Buildings, net | - | 11 | 10 | 10 | 8 | 7 | 6 |
|---|
| Machinery and equipment | - | 195 | 210 | 217 | 261 | 293 | 293 |
|---|
| Accumulated depreciation | - | -150 | -162 | -167 | -184 | -203 | -225 |
|---|
| Machinery and equipment, net | - | 45 | 48 | 50 | 77 | 89 | 68 |
|---|
| Tools, furniture and fixtures | - | 25 | 34 | 38 | 38 | 38 | 39 |
|---|
| Accumulated depreciation | - | -18 | -23 | -29 | -31 | -31 | -31 |
|---|
| Tools, furniture and fixtures, net | - | 7 | 10 | 9 | 6 | 7 | 8 |
|---|
| Property, plant and equipment | - | 63 | 68 | 68 | 92 | 103 | 82 |
|---|
| Patent right | - | 76 | 70 | 64 | 59 | 53 | 48 |
|---|
| Trademark right | - | 1 | 1 | 1 | 1 | 1 | 0 |
|---|
| Software | - | 6 | 19 | 14 | 9 | 8 | 4 |
|---|
| Intangible assets | - | 87 | 90 | 80 | 68 | 62 | 53 |
|---|
| Investment securities | - | - | - | - | 305 | 303 | - |
|---|
| Long-term prepaid expenses | - | 89 | 79 | 68 | 58 | 48 | 39 |
|---|
| Other | - | 20 | 22 | 22 | 21 | 21 | 19 |
|---|
| Investments and other assets | - | 110 | 101 | 90 | 383 | 372 | 57 |
|---|
| Non-current assets | - | 260 | 259 | 238 | 543 | 536 | 191 |
|---|
| Assets | - | 3,622 | 2,660 | 2,049 | 4,719 | 4,329 | 3,821 |
|---|
| Accounts payable - trade | - | - | 24 | 62 | 49 | 49 | 76 |
|---|
| Current portion of long-term borrowings | - | - | 160 | 160 | 160 | 160 | 160 |
|---|
| Accounts payable - other | - | 42 | 39 | 39 | 64 | 196 | 202 |
|---|
| Accrued expenses | - | 61 | 74 | 47 | 2 | 5 | 4 |
|---|
| Income taxes payable | - | 7 | 7 | 7 | 28 | 6 | 10 |
|---|
| Deposits received | - | 3 | 4 | 4 | 5 | 4 | 3 |
|---|
| Provision for bonuses | - | - | 0 | - | - | 1 | 0 |
|---|
| Current liabilities | - | 114 | 308 | 319 | 308 | 422 | 456 |
|---|
| Long-term borrowings | - | 1,601 | 1,413 | 1,253 | 1,093 | 933 | 773 |
|---|
| Long-term accounts payable - other | - | 224 | 212 | 199 | 186 | 174 | 161 |
|---|
| Provision for retirement benefits | - | 31 | 37 | 46 | 51 | 48 | 54 |
|---|
| Non-current liabilities | - | 1,856 | 1,662 | 1,499 | 1,331 | 1,155 | 988 |
|---|
| Liabilities | - | 1,970 | 1,970 | 1,818 | 1,639 | 1,577 | 1,444 |
|---|
| Share capital | - | 1,900 | 1,900 | 2,000 | 3,808 | 3,300 | 2,938 |
|---|
| Legal capital surplus | - | 700 | - | 100 | 1,908 | 221 | 196 |
|---|
| Capital surplus | - | 700 | - | 100 | 1,908 | 221 | 196 |
|---|
| Retained earnings brought forward | - | -948 | -1,210 | -1,869 | -2,637 | -779 | -764 |
|---|
| Retained earnings | - | -948 | -1,210 | -1,869 | -2,637 | -779 | -764 |
|---|
| Treasury shares | - | - | - | - | - | -0 | -0 |
|---|
| Shareholders' equity | - | 1,652 | 690 | 231 | 3,080 | 2,742 | 2,370 |
|---|
| Share acquisition rights | - | - | - | - | - | 10 | 7 |
|---|
| Net assets | 2,511 | 1,652 | 690 | 231 | 3,080 | 2,753 | 2,377 |
|---|
| Liabilities and net assets | - | 3,622 | 2,660 | 2,049 | 4,719 | 4,329 | 3,821 |
|---|