Even F-droid has half a dozen apps to learn the writting system.
The problem with learning this, is that when you know katakana and hiragana perfectly, you are still in the same learning spot that you are today to learn finnish or euskera, and much worse than german or danish (they have things in common with english).
- Skritter - Kana (free) - Japanese!
The parent comment is reasonable. Learning hiragana also takes no more than a week or two if you’re actively practicing writing.