Hentai is anime and manga pornography. 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"). In addition to anime and manga, hentai works exist in a variety of media, including artwork and video games (commonly 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.