"Fun" Fact: This type of stuff getting more extreme is also partially gross American nerds' fault, since the Japan's dropping fertility rate means that one of the things still propping up the anime/anime porn industry is American dollars (not as much as the boom years of last decade, but more than enough to have an influence), so it creates a godawful feedback loop of fetishes. For example, there's a much less reprehensible, but still weird and porny, monster girl harem comic that is apparently only moderately popular in Japan, but has consistently been #1 on the New York Times' Best-Seller List.