Hmm... I haven't search japanese sits in years but one of the old standbys was, and presumably still is
http://www.tinami.com/
If you've visited jpaanese galleries before I'm sure you can figure out how to read the english descriptions in the status bar and such.
And of course visit the links section of sites you like, usually you can find similiar sites in the lniks section.
http://www.tinami.com/search/
is probably the easiest way to find japanese art of a specific type. again they added a lot more options ( in text damn them) so I'm not sure what all the buttons do, but a lot of them are pretty self explainatory.
i.e. the SF button is for "Sci Fi themes"
and the "Bleach" button will find sites that do bleach fanart and so on and so forth.
You could try slapping the old babelfish on it as well.
Tinami does have hentai on it but the default options should keep the sites with nothing but pr0n to a mininium.