I've used a bunch of open source Japanese keyboards: Mozc[0] (might be related to Gboard? haven't used gboard but the app is based off the same source code that

I've used a bunch of open source Japanese keyboards: Mozc[0] (might be related to Gboard? haven't used gboard but the app is based off the same source code that powers Google IME), nicoWnnG[1]. I'm not sure how well they fare compared to proprietary keyboards but they've been good enough for my occasional use of Japanese. [0]: https://f-droid.org/en/packages/org.mozc.android.inputmethod.japanese/ https://f-droid.org/en/packages/org.mozc.android.inputmethod... [1]: https://f-droid.org/en/packages/net.gorry.android.input.nicownng/ https://f-droid.org/en/packages/net.gorry.android.input.nico...