Sexual desires are from God, and they are not bad. However, like other appetites, they have to be guided and used according to the created order. What is happening in Japan is that excess has led to the opposite extreme of repression. Normal sexual desires for another person have been replaced by porn, and in turn this allows people to avoid normal sexual relationships.And, when you have spend years watching hentai porn, your appetites for the normal are almost completely distorted as to be unrecognizable.
***When people talk about pornography being a 'victimless crime,' that is plain wrong on many levels. Not only are the 'actors' in porn victims of degradation, but all of society suffers from the objectification of humanity.