TBH A LOT of hentai is rapey af, that and the fact that Japan loves it's immortal lolis... IDK.... they have some issues. That being said show me a place where the people don't have some mental hang ups.
Some people are so desperate for sex and have such low self-esteem that they view rape as there only way of getting laid... or are just the WORST kind of person and just don't give a fuck about anyone other than themselves. To some people it might just be a fetish that they may never act on. Again IDK, shits weird my dude.