do you know basic japanese? If you do, then there's poonani galore... if not, you're pretty screwed unless you've got a LOT of $$$... there's generally a strong negative image of foreigners in japan, so all the hotties usually work at the japanese-only places.
here's a couple of very useful websites if you can understand some japanese:
http://ikebukuro.kir.jp/
http://www.kabukicho.info/
If you can't speak japanese, you'd have better luck going to roppongi, shibuya, or shinjuku and just trying to pick up a chick at a club...
of course if you have wads of cash to blow, there's always the tourist-based places (kinda like swedish touch here):
http://www.miss-platinum.com/escorts/
have fun man! Tokyo's not bad, but IMHO, Fukuoka's MUCH better...
