I can't say absolutely for sure, let me tell you a little story, and you can judge for yourself:
About three years ago, I was vacationing in Japan and I kind of hooked up with this guy at some kind of festival in Kyoto. Nothing serious, he was just showing me around and stuff. He was actually Japanese American, but living in Japan for an extended period. His English was perfect, better than his Japanese I think.
Anyway we wanted to get a drink and I was teasing him a little, saying since he was Japanese he should take me somewhere interesting that tourists wouldn't normally go. But of course he wasn't really a local either, so we just wandered around for quite a while. And we ended up at the door to this place in some alley. There was music coming form inside, but other than that you could just barely tell that it was anything other than a residence. But the guy (Takumi was his name), knocks and the doorman opens it. First he looks at Takumi, then at me, and I could tell he's saying we can't come in. At first we both thought it was because I'm white (I know that sounds bad, but Japanese people can be just as racist as anyone else, so it wasn't an unreasonable thought), but then Takumi got a REALLY weird look on his face, apologized (I assume) and turned to leave. As we walked away--rather quickly--I asked him what just happened. And he said quote "The guy said it was an incest club." I was like "what!?" but he swore it was true, and went on to explain that it's BYO relative, and since we obviously weren't related that's why we weren't allowed in.
So there you have it. It's possible he was pulling me leg, or maybe covering up that it really was a race thing. But I have no reason to think he wasn't telling the truth.