Any perverse or abnormal act could be hentai, such as committing shinjū (love suicide). It was Nakamura Kokyo's journal Abnormal Psychology which started the popular sexology boom in Japan which would see the rise of other popular journals like Sexuality and Human Nature, Sex Research and Sex. Originally, Tanaka Kogai wrote articles for Abnormal Psychology, but it would be Tanaka's own journal Modern Sexuality which would become one of the most popular sources of information about erotic and neurotic expression. Modern Sexuality was created to promote fetishism, S&M, and necrophilia as a facet of modern life.
The ero-guro movement and depiction of perverse, abnormal and often erotic undertones were a response to interest in hentai seiyoku.
