Yeah, you'll more than likely need some, if not excellent, Japanese language ability. I was with one a few years back at a hotel health group that no longer exists. It was actually quite reasonable. There's some reviews for a place called deli-ueno that's foreigner friendly and has porn stars in their stable, but I can't say whether those porn stars themselves will see foreigners, and they are fairly pricey (although still a lot cheaper than most of the porn stars that escort in the US).
Maria Ozawa was available for delivery health a while back and is still one of the cover girls for Tora Ana, but I don't think she works there any more, and that org is NOT foreigner friendly. Not really on topic, but there's a lot of Japanese porn stars (Maria Ozawa, Aoi Sora, Aino Kishi, etc) that do fairly well outside of Japan. Sort of like if Shannon Tweed or Pamela Anderson had a long term hard-core porn career and then got into the B-movies they did.