Hentai is a Japanese word that can be used to mean “metamorphosis” or “abnormality”. In Japan “hentai” has a strong negative connotation, and is commonly used to mean “sexually perverted”. In the West the term is used as slang for sexually explicit or pornographic comics and animation, particularly Japanese anime, manga and computer games (see Japanese pornography).

In Japan sexually explicit material is more often referred to as “jū hachi kin”, “ecchi/Hentai anime” (sexual/pornographic anime), “seinen”, or with the prefix “ero-” (derived from “erotic”). Hentai anime and manga allow elements of sexual fantasy to be represented in ways that would be impossible to film. This may include portrayals of sexual acts which are physically impossible, unacceptable in society, or run counter to social norms. Examples include extreme bondage, creatures with tentacles, and other fetishes.

Shunga artists like Yoshitoshi and Kuniyoshi showed gang rape, erotic crucifixion, and even forced late third-trimester abortions by a “cannibal witch.”