Having been to Japan 5 times, I've managed to satisfy my curiosity at THC in Shinjuku. You dont need to speak Japanese as most of the girls understand English and like many things in Japan, you use a vending machine to choose the girl, costume and services. Once paid for you go the the room and they'll do your business so you don't even have to talk to them if you don't or can't.
However although it is fascinating and decorative, the sex it self isn't all that as they tend to let you do all the work urgo squeeky sac of potato.