The solution to all your Japanese fangames troubles are in this very thread! Links provided.
Implying you read it carefully and do stuff consequtively. Otherwise, it's your problem.
Still post here if something doesn't work.
There we go:
1) Make sure you have Japanese language installed on your system - what the hell are you doing in /fg/ without that anyway?..
In case you're still here w/out it:http://www.microsoft.com/download/en/details.aspx?displaylang=EN&id=8289
But you most probably have it already.
2) Install Applocale - it works both for XP and Win7. http://alcahest.perso.sfr.fr/perso/apploc/applocale.html
There is also a patch and some register keys on the same page, install'em all. Well, when you read that page, it's all pretty obvious.Post too long. Click here to view the full text.