Need to study Japanese on the go? This app lets you study Hiragana and Katana in an easy to use swipe flashcard interface. Swipe right if you know it, swipe left if you dont. At the end, you can study again just the cards you got wrong.
Benkyou also has a WaniKani intergration that lets you study all levels using your WakiKani API key. Study radicals, kanji and vocabulary for each level, and review your "Recently Unlocked" and "Critical Items" in preparation for your reviews.