Juken is a minimalistic review app for WaniKani optimized for speed. It eliminates the need for typing; just recall, reveal and swipe.
The user experience was inspired by the popular flashcard app Anki in the sense that it allows you to reveal the answer instead of having to typing it out, and it features a Tinder-like swipe gestures to quickly submit your answers. Just login with your WaniKani Personal Access Token and start swiping.
Note: This app requires a WaniKani account, which could be obtained at https://wanikani.com