Sorry I didn't reply until now... these forums are so dang big... lost the thread.
Maciamo:
Hostessing is not even legal in Japan, but like prostitution it is just for the international image.
Do you have a source for this? While I agree that just b/c something is in plain view doesn't make it legal, hostessing is. Afterall -- there's not even any touching, the advertise in papers, cops never shut them down*. Prostitutes usually don't get busted for prostitution... but they'll every now and again raid a "shop" and send all the illegal immigrants (usually Chinese) on their way.
As for the Phillipinos & Russians, you're more likely to find places with that certain flavor outside of Tokyo. Err... maybe I should say, "you're more likely to find a group of those nationalities active in the scene outside of Tokyo." Not to sound like a pig, but Phillipino's in Tokyo are more known for for being nannies and maids. That's not to say they don't exist though.
The hostessing scene in Tokyo, at least in Roppongi, is a large part "white chicks with fake guns" to put it bluntly. A stroll through that area at 7AM will show you, as I used to cycle through their each morning to get to work. The thing is, there are so many hostessing places, just about any girl can do it. I think about half of the girls I was friends with in Japan at one time or another hostessed.
Kendhe:
Those nightmare stories of women getting sold into prostitution usually don't happen to westerners. Sure, it's not impossible, but I seriously doubt it'll happen. The women I was referring to all seemed to have gotten to Japan on the same reference, and I assure you were having a great time. I do agree though, that speaking at least survival level Japanese and being IN Japan will help your project immensely.