It's hard to generalize what a Japanese girl finds attractive but from my experience, they currently like men who are almost borderline feminine. Slender build, fair complexion, no facial hair, etc.
But either way, there's a lot more to picking up a girl than fitting that stereotype. If you speak Japanese and make the right moves, you should be able to pick up most of the girls in Japan... providing you're not too picky. ie. Some girls like the OL's in Ginza will take some extra effort... like an Amex Black card.
