Learn Japanese! JA Sensei is an application that lets you learn and practice Japanese anywhere: hiragana, katakana, kanji, vocabulary, phrases, numbers, lessons. The KANA and KANJI modules are free.

Here are the current features available:

JAPANESE LESSONS MODULE
23 Japanese lessons to learn the basic concepts and grammatial structures
Each lesson contains a Japanese text for you to read and learn real Japanese sentences, a grammar page, and a culture page to learn Japanese customs and understand how they think

KANA & KANJI MODULES
Learn Hiragana/Katakana progressively by levels
Learn Kanji by Jouyou Grades and JLPT levels
Add any Kana or Kanji to your personal list and practice only on your list
Listen to the pronunciation of each Kana
Get for each Kana and Kanji 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, Katakana AND Kanji 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

PHRASEBOOK MODULE
500 Common Japanese phrases for real life communication or use it as a phrasebook
Learn Japanese phrases with audio clips (download)
Keep your favorite Japanese phrases in your personal list
Browse the Japanese phrasebook quickly and instantly by simple typing a few letters or a word

VOCABULARY MODULE
1400 words with audio clip by a native speaker
Take audio quizzes!
Create your personal list of Japanese words
Comments are added to explain the word when necessary
Search for any word from English or Romaji

NUMBERS MODULE
500 numbers with audio clips by a native speaker
Listen and understand numbers from 0 to 10,000
Take audio quizzes
Create your personal list
Search any Japanese number from its numerical value or Romaji
Read numbers in Kanji, Romaji or numerical value