Japan is well known for "odd" sexual fetishes. The Japanese live in a relatively repressive culture and women are typically expected to be submissive.
There are plenty of examples of torture and rape porn, not to mention tenticle porn, etc. If you do see Japanese porn where the girls are enjoying themselves, they are blasting out high-pitched squeals. Yup, the men also have a thing for young girls.
There are many theories on what brought about these fetishes over the years. One concrete answer is that the pixillation of genitalia comes from government rules.
All cultures have different things that turn them on. Plenty of people find popular porn from western cultures odd. That said, torture or rape porn from any culture is a total buzz kill for me.