When it comes to media standards, Japan is about as open with sexuality as US is with violence but the reverse is not true, things usually get censored when these countries port media to each other based on the perceived clash of sensibilities (I mean, look at all the senien and even shonen anime with excessive amounts of violence. For example: Jojo's was only recently moved from Shonen Jump to a senien magazine with Part 8 and that's probably soley due to the protagonist's odd gonads being a key plot point but IDK also hilariously a lot of the blood and stuff got censored in the US release, talk about irony...).
Does perversion factor into things? Well, far as I can tell, yes actually but only so much as the Japanese apparently expect people to grow out of it as adults to focus on doing their jobs. That's just something I've pieced together on things I've heard about their culture though. I could be wrong.