As one example, animated or drawn child pornography is perfectly legal there. There have been multiple legal rulings reinforcing that. Western audiences find that horrible, for the most part.

Actual pornography is censored in Japan however, and many of the people I've talked to there find uncensored real pornography to be far more offensive than drawn pornography.

You can also find parasocial writings where people will post their imagined lives with public figures. There are a ton of topics that fall under this advisory. It's a completely different culture, and many people not from there make assumptions about what's acceptable from what is popular wherever they are from. That rarely looks anything like the reality there (and is true for anywhere that happens).