JA Sensei 0.8.0
the author of this app says:
JA Sensei is an application that will let you learn and practice Japanese anywhere for free.
Here are the current features available:
Learn Hiragana/Katakana progressively by levels
Add any Kana to your personal list and practice only your list
Listen to the pronunciation of each Kana
Get for each Kana your overall right answer percentage to know on which ones you should improve
Increase the quiz difficulty progressively: easy, medium, hard
Add a countdown to limit the time yo have to answer (for medium and hard difficulty level)
Practice your writing skills and learn how to draw Hiragana and Katakana properly
The setup options for quizzes are saved so that you don't have to define them every time
Quickly switch between Hiragana/Katakana in the learning area
Search a kana quickly by typing only one letter that it contains
Many more modules are planned to be integrated (kanji, numbers, etc.) so give it a try to see how it looks so far and expect more soon.