Yuka Osawa does movies for Dandy with white and black men, mostly black men. She did have one exclusively for white men with Lee Stone and some other guys. The title is "Big white dicks" how imaginative...
Other than that, I really couldn't tell you because I don't care for Japanese porn. From living in Japan, I can tell you that there is a TON of bm/jf stuff there. There's also a lot of jm/wf stuff too. There's probably more American porn featuring am/wf than Japanese stuff featuring wm/jf.