I went to Japan almost 5 years ago for a month. It was...a good trip but weird. I went to learn more about rope bondage/shibari (like people tied up in the air by rope only)...I got throw into a really misogynist area of sex in Japan as a foreigner, especially because I went with another women. The courses we were taken over the month was teach by an Western man who has lives in Japan since the 70s and basically just embrace the culture...but anyways. Its really one sided.
Went to a few sex shows which were interesting? Never seen someone put different type of coloured enema up their ass and get spin while tied in the air and shoot it on the viewers. Yet again porn is everyone,especially hentai and everything that is barely legal...and hell not even. They change the laws since 2013 but when I went, went to a few sex stores and there was obvious child pornography sell right in front of your eyes and not 18 years old that may look 15 but obvious 8 years old. They use to have the laws that its illegal to produce, but legal to sell and carried (so if you dont know where it come from....)
Consent in somewhat sexual setting is not really a thing, went to a sex club with my partner and in broken english was grab a lot, arms, legs, breast, saying "sex with me" basically.
Japan is a lovely country, people are really friendly, but when it come to more secular groups, aka underground like bdsm or sex work, yeah it all change