i don't really rely on brush in fact, since the characters are put from a convertion of a certain key, it becomes a headache if you must remember which original key will give "that sign", rather than a possibility to type yourself with a program or copy-paste. (in the other hand, it's quite easier to have fantasy style in a faster way) but thanks anyway.
EDIT :
at last, i have in fact found the ridiculous answer : iyou can only use Unicode font (or something like that XD)... (i'm not really an expert of coding, but sounds like PS just use font within their respective character range, which isn't the same with "unicode" used in text software like word, notepad etc saddly)
i dunno how it is shown in your software, but in mine (PS 6.0, pretty old i know, but it's enough to me ^^), fonts are separeted. the fonts which can use hiragana/katana/kanji and all are group "MS xx" (no in the common mass, but some fonts in their own category) and group "Arial Unicode MS" + the fonts below it. (this should be possible to anyone, since windows use theses fonts if you installed the asian pack from the languages, in the control panel)
http://img175.imageshack.us/my.php?image=fonts1km8.jpg
http://img175.imageshack.us/my.php?image=fonts2ym5.jpg
if anyone can explain/confirm, it would be great ^^" (but whatever, it's finally fixed !
)