Pocket Sensei is a Japanese language learning tool. It teach you more than 8000 most common words, over 2000 kanjis and hiragana and katakana grouped by Japanese Language Proficiency Test (JLPT) levels 1 - 5.
Tool asks different character, reading and meaning combinations and remembers your progress. Works completely offline.
You can add widgets on your homescreen to make the learning easier that ever.