The following two documents are made public to explain Japanese Linux matters. Both are written in Japanese and, unfortunately, no English version is available.
They are in the jd disk set of JE, and periodically posted on fj.os.linux and some BBSs in Japan.
``Linux Jouhou memo'' by Y. Hiro Yamazaki hiro@ice3.ori.u-tokyo.ac.jp
``JMETA-FAQ'' by Tetsu Ono
ono@eiehost.gee.kyoto-u.ac.jp
There is a book in English which will help you understand how the Japanese language is handled on computers, including the complicated issue of the character code sets.
Understanding Japanese Information Processing Ken Lunde O'Reilly & Associates Inc ISBN 1-56592-043-0
You may find it easily, because the title is printed in large Kanjis.