This is one of my favorite language resources on the web.
"Tadoku" means "wide reading" or frequent reading (it combines the kanji for "many, frequent, much" - 多 - with the kanji for "read" - 読). It gives even beginning Japanese students a chance to read on a wide range of topics.
Even many of the easiest books contain cultural lessons for non-Japanese readers - for example, Akai (Red) shows Japanese torii structures and a red thread of destiny. Meanwhile, Aoi (Blue) starts out by showing a series of blue objects - a bike, a car - but ends with images of things that, to American eyes, look green: green apples, green vegetables, and a green traffic signal - teaching readers that non-Japanese people and Japanese people think of blue and green in different ways.
The Level 0 stories are short but delightful. They're incredibly varied, with topics including colors, food, weather, and the adventures of pets.
You can download the books for free, and many of them have audio as well.
A short tadoku break is one of my favorite parts of the day. I highly recommend the tadoku books to anyone learning Japanese.