Hentai is a style of Japanese erotic/pornographic anime and manga. A loanword from Japanese, the original term (変態) does not describe a genre of media, but rather an abnormal sexual desire or act, as an abbreviation of hentai seiyoku (変態性欲, “sexual perversion”), and is also used to refer to persons who hold or do such desires and acts, often translated to English as “pervert”. In addition to anime and manga, hentai works exist in a variety of media, including artwork and video games (mostly known as eroge).

The development of hentai has been influenced by Japanese cultural and historical attitudes toward sexuality. Hentai works, which are often self-published, form a significant portion of the market for doujin works, including doujinshi. Numerous subgenres exist depicting a variety of sexual acts and relationships, as well as novel fetishes.

The hentai genre can be divided into multiple subgenres, the broadest of which encompasses heterosexual and homosexual acts. Hentai that features mainly heterosexual sex occur in both male-targeted (ero or dansei-muke) and female-targeted (“ladies’ comics”) form. Those that feature mainly homosexual interactions are known as yaoi or Boys’ Love (male–male) and yuri (female–female). Both yaoi and, to a lesser extent, yuri, are generally aimed at members of the opposite sex from the persons depicted. While yaoi and yuri are not always explicit, their pornographic history and association remain. Yaoi‘s porn usage has remained strong in textual form through fanfiction. The definition of yuri has begun to be replaced by the broader definitions of “lesbian-themed animation or comics”.

Hentai is perceived as “dwelling” on sexual fetishes. These include dozens of fetish and paraphilia related subgenres, which can be further classified with additional terms, such as hetero or homosexual types.

One other famous subgenre is futanari (hermaphroditism), which most often features a chick with a dick.