Have you thought of putting out Japanese versions of Wakaba/wakaba zero? It'd be wild if 2chan or one of the smaller japanese boards started using it :D
In Wakaba, there's a strings_j.pl in extras.zip that contains the old japanese strings. However, some of the new stuff I've added is not properly translated. I'd really like some help from someone who's better at japanese than me to fix it up properly.
Similarly, there's a templates_j.pl for Kareha, that contains at least a partial japanese translation, done mostly by cut-and-paste. Squeeks has one board up using that on http://4-ch.net/, but I can't reach that at the moment.
Here we go: http://4-ch.net/nihongo/
Sounds like a job for http://cerealandmilk.net/iichan/ ?