These are all the recommendations I've found on this forum, plus some I've discovered myself, for easing into and practicing reading japanese. Perfect for starting a 多読 library.

１０分で読める
http://www.kodomonohon.jp/goods/series/n...00erw4.php
Series of books with stories you can read in 10 minutes (if you are japanese) graded by level, from 一年生 to 六年生.
About 20 volumes.



なぜ?どうして?
http://amzn.to/Q5hiTL
By the same publisher of １０分で読める, series of books that explains science to kids, graded by level.
At least a dozen volumes.



民話と伝説 呪いの巻物
http://www.kaiseisha.co.jp/index.php?pag...&Itemid=78
Scary stories about monsters, ghosts, mysteries and wonders.
12 volumes.



グースバンプス
http://ja.wikipedia.org/wiki/%E3%82%B0%E...7%E3%82%B9
日本語版 of the legendary Goosebumps series. Who hasn't read one of these?!
10 volumes.



魔女の宅急便
http://ja.wikipedia.org/wiki/%E9%AD%94%E...5%E4%BE%BF
The books Miyazaki's movie (Kiki's Delivery Service) is based on. Very well recommended around here.
6 volumes.



齋藤孝のイッキによめる! 名作選
http://www.bookclub.kodansha.co.jp/books/meisaku/
Fairy tales from Japan and around the world.
At least a dozen volumes.



マジック・ツリーハウス
http://kids.mediafactory.co.jp/magictree...eries.html
http://ja.wikipedia.org/wiki/%E3%83%9E%E...6%E3%82%B9
日本語版 of the famous Magic Tree House series.
At least 32 volumes.



That's more than 100 books, it should keep you busy for a while
If you have more recommendations please post them!

are they really for beginners? I feel like
マジック・ツリーハウス　>> upper-beginner
なぜ?どうして?, １０分で読める (1-3 grade) >> upper-beginner
the rest are for intermediate level

I recommend
魔女の診療所 series (小学中級から）
http://www.bookclub.kodansha.co.jp/flash/285198/

若おかみは小学生 series (小学中級から）
http://www.bookclub.kodansha.co.jp/flash/148613/

超絶不運少女 series (小学中級から）
http://www.bookclub.kodansha.co.jp/flash/285212/

These will come in handy once I'm done with RTK Thanks for posting the book titles and brief descriptions.