Reporting back: no luck while I was there. There were plenty of massage parlours, but none that would accept foreigners. Some of the places had websites, but were clearly not catering to English speaking tourists. It's strange that in a such an extremely fetishized culture, they would not have this. I mean, all you have to do is go to the bottom floors of many shopping centres to see hundreds of young girls all dressed up in various anime/cosplay outfits looking like their favourite characters. I know they do it for themselves and to fit into a subculture there, but the Japanese people have a very strange way of expressing their perverseness. It's all white shirts, dress pants/skirts, prim and proper, holding a fan and dabbing their face with a Hello Kitty handkerchief sitting in silence on the subway, while the young girl next to them is scantily clad in a very revealing short private girl mini-skirt with make up like sailor moon. No eye contact by anyone. Trains just for women, which are mostly used by school children. Anyway, Japan is still an amazing place to visit, and some of the woman there are just incredible. There is not shortage of beautiful young ladies there, but just like anywhere, also a fair share of butter faces.