in addition to T195816:
Japanese is often written in latin script:
example: https://www.wikidata.org/wiki/Lexeme:L346031
ja | 了解 |
ja-kana | ロジャー |
ja-latn | Ryōkai |
Some latin japanese strings are currently tagged with ja-x-Q53979348 (https://www.wikidata.org/wiki/Q53979348)