Kana Practice is an app I did for the Apple Watch to memorize Japanese syllabaries (Hiragana and Katakana). It shows you a symbol and you have to guess the pronunciation. The app adapts as you use it and ask you more often the ones you have failed.
Kana Practice is written in Swift and created using XCode.
The first version of the app was published on 29th September 2018
You can find Kana Practice here: https://apps.apple.com/us/app/kana-practice/id1437713698