A lot of Japanese enterprises make the decision not to deal with foreigners at all.
This is often construed to be racism, but by and large, it's due to the language barrier. You see this quite often in restaurants, and particularly in 'izakaya' pubs, where the staff are unable to translate the menu or explain what the various dishes are. It's just too much trouble.
Japanese is my second language, yet I am sometimes refused entry at first. Once I speak to them, I am welcomed in.
When it comes to gay saunas, where language isn't really required, their refusal to deal with foreigners is, IMHO, purely racist. Foreigners are seen as the transmitters of all kinds of sexual diseases, whereas if you have sex with a fellow Japanese, you are considered safe.
Friends of mine joined a sex club in Ueno when we were at university. When I turned up with them to also join the club a few weeks later, I was met with a very polite, but very firm, refusal.
I eventually got in, but I had to jump through all kinds of hoops.
I'll leave that story for another time.
I'm off to tokyo tonight for a couple of weeks to see the cherry blossoms.
Unfortunately, I'm going with some straight friends, so I won't be able to check out some of the gay establishments. However, I'm thinking of shunting them off to Kyoto for a few days to give myself a bit of space. My problem is convincing them go travel by themselves, as none of them speaks Japanese and are somewhat nervous.