I've been visiting Tokyo quite frequently for the last couple of years (usually, every two months or so). Being originally from Russia, I was naturally inclined to seek Russian girls for fun when I am on my trips.
Initially, I visited Kabuki-cho area (close to Shinjuku station). Most of the places there are closed for gaijins, like myself, and those who accept foreigners have usually only Asian girls (Koreans, it seems). There are a few hostess bars, where one can find Caucasian girls, but hostess bar is a natural ripoff, in my opinion.
Later, I discovered Roppongi. More Caucasian girls, even some Russian places, but all of them are essentially hostess bars (same problem -- you waste money with little or no result).
I finally decided to try escort services. The trouble was that most of the escorts in Tokyo also have Japanese ladies, so I was pleasantly surprised
to find "Alla Escort" (not sure how about the commercial restriction in this forum, and whether if I should give the URL, but anyone equipped with Google can easily look it up).
I gave Alla's site a try when I found her Web page, and I've been sticking with her girls ever since. Her Web site is English and all girls speak English
as well (not that I care about the latter part, since I prefer communicating
with them in Russian -- that gets my juices flowing).
The girls change from time to time; among the current ones, I tried only Olga.
At that time, I was interested to experience a dominatrix, and Olga handled
that quite well (apparently, she can play a slave role as well).
Depending of the girls availability, a lesbian group seems to be also available,
but I never had time to sample that.
Looking forward to get back to Tokyo soon...