I´ve recently found a publisher with lots of jepanese language excercises and some free (audio) downloads.
Try
White Rabbit Press – Japanese Kanji and Kana Flashcards, Tokyo Realtime Audio Tours and more…
There are for example books for reading in different levels of difficulties. (level 0 (0-400 Characters per story with Kana-Translation ) to level 4 (with 5000-10000 Characters per story)
But I´m not able to recommend a specific course book