Japanese sexuality
Japan is kind of weird about that. But I think it makes more sense if you realize that it's not victorianism so much as it is a germ phobia. People live awfully close together in Japan, and they are very conscious of hygeine. I've been to Japan, and one thing I noticed right away is that in Japan, you never touch a door. Every door in every public building is automatic. And of course, they have the shoe rituals. When you step into someone's home (or your hotel room), you leave your street shoes at the door, and put on a pair of slippers. When you go to the bathroom, you remove the house slippers and wear bathroom slippers while you're in the bathroom. Considering that a lot of people in the major cities like Tokyo live packed in like sardines, perhaps it's not so unreasonable. (Although I did see some peculiar things. Some people wear face masks or filters whenever they walk outside in Tokyo. One morning, I watched one guy who was wearing a mask, presumably to protect him from pollution... but then every so often he had to push it aside to take a drag off of his cigarette!)
Sexuality per se, I don't think they really have a problem with, at least not the younger people. I heard (didn't go there) about one co-ed bath house in Tokyo where, in order to get from the lockers to the bathing pool, one has to walk across a glass bridge that goes directly over the pool... giving everyone already in the pool a nice view!