It doesn't matter how dark or bizarre, if you can think of it there will a small club dedicated solely to it in Japan.
eg. Have you seen Tokyo? Shibuya is Rule 34 ; love hotels, bestiality restaurants, sex robot love parlors, cosplay sex clubs, soapland, transvestite soapland, rape play, yakuza swingers, anime bondage, knitting bondage. It's nasty!