Hentai (変態 or へんたい, Hentai?) listen (help·info) 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" (18禁; prohibited for sale to persons under 18), "ecchi/Hentai anime" (sexual/pornographic anime), "seinen" (成年; adult, not to be confused with 青年 young adult), or with the prefix "ero-" (derived from "erotic").

The Dream of the Fisherman's Wife, an shunga (erotic) woodcut made circa 1820 by Hokusai.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.

Meaning of the word
In the 1914 translation of Richard von Krafft-Ebing's Psychopathia Sexualis, "psychology of abnormal sexuality" was rendered in Japanese as 『変態性慾心理』 (Hentai Seiyoku Shinri).

In Japanese the word hentai is a kanji compound of 変 (hen meaning "change" "weird" or "strange") and 態 (tai meaning "attitude" or "appearance"). The term is used as a shortened form of the phrase 変態性欲 (hentai seiyoku), or "sexual perversion." In slang, 変態 (hentai) is used as an insult meaning roughly "pervert" or "weirdo". The term is not often applied to pornography in Japan. Instead, terms such as 18-kin (18禁, literally "18-prohibited") meaning "prohibited to those not yet 18 years old", and seijin manga (成人漫画 "adult manga") are used when referring to pornography.

The English use of "hentai" is more similar to the way the Japanese use the slang term エッチ (H, etchi, often spelled ecchi), which refers to any sexually explicit content or behavior. Etchi is simply the spelling-out of the Japanese pronunciation of the letter H. The origins of this term are uncertain, but it may be a shortened form of hentai used as a polite codeword in the 1960s.

"H" in Japan is now broadly used to refer to all sexual content or activity, so "H manga" are manga with sexual content. Also, the term "ero" (エロ), short for "erotic" but closer in meaning to "porn", is now used more often instead of "H".

Exactly how the term hentai came to refer to all sexually explicit content in American anime fandom is unknown. With the rise of the World Wide Web, however, the term was extensively promoted by pornographic sites selling access to (frequently bootlegged) erotic manga. Banner ads promoting these sites might, for instance advertise "live girls and hentai", with the latter meaning erotic manga as opposed to photographs. Compare otaku for another word altered somewhat in this transition.

Hentai classification

There are two main categories of hentai: works that feature mainly heterosexual interactions (often abbreviated "het" by its readers), and those which feature mainly homosexual interactions. This second group can be further split into yaoi and yuri styles. Yaoi refers to homosexual male pairings, and yuri to lesbian pairings.

Yaoi commonly features males of ambiguous gender in both physical appearance and mannerisms called bishōnen, which literally means "pretty boy". Some feature biseinen ("beautiful man"), males of more masculine appearance than bishōnen. Less common are bara--larger, often heavily muscled and sometimes hairy males, the yaoi counterpart of the traditional "bear" in gay pornography, as well as oyaji ("daddy" or "uncle"), featuring middle-aged and elderly men. Yaoi also exists outside of the hentai genre, since it is an ambiguous term that is applied to any form of anime that includes male homosexuality. However, it is different from shōnen-ai (literally, "boy-love"), in which two males simply express romantic feelings for each other and never actually have sexual relations. Women interested in Yaoi are called "Fujoshi" (腐女子), which means "Rotten girl" or "Rotten Woman."

Yuri is very similar to yaoi, except that the focus is on homosexual female interactions, and the females in a typical yuri illustration or animation tend to be far less realistic than the males in yaoi. The females in yuri are known as "bishōjo," which, predictably, translates as "pretty girl". Shōjo-ai ("girl love") is the female equivalent of shōnen-ai.

The scope of hentai encompasses the entire range of sexual fetishes, including:

• Bakunyū, the depiction of women with large breasts. Literally translated to "bursting breasts".
• BDSM, focusing on domination through use of ropes, tools, sex toys, and elaborate devices. Themes can include empowerment, restriction, and submitting to sexual urges.
• Bestiality
• Breast-oriented torture and Breast bondage, BDSM practices focusing on breasts, many times coupled with Bakunyuu, but usually not as severe as Guro.
• Bukkake, a common representation of a female having as many males as physically possible ejaculate on her. Often depicted in public or in areas with a large number of males present. The woman is expected to swallow all of the ejaculate and it is also polite to milk every man of their gooey cum.
• Coprophilial and urolagnial is fairly common in hentai as well. But is portrayed in more exaggerated forms, such as bowel movements that border on elephant size to over-the-top scenes of enema play that are more cartoonish.
• Deformity
• Ecchi, focusing on nudity, partial nudity, and provocative clothing rather than pure sex.
• Futanari (Futa), a depiction of females who have some form of male genitalia. Occasionally, the size of the penis and/or testicles is inflated to proportions that are physically impossible. The male genitalia can also come from inside the vagina, or right above it, in the latter case this creates a female body with both sexes.
• Guro, focusing on imaginative gore and mutilation.
• Incest, sex with a close family member.
• Klismaphilia, erotic enema play, usually used in BDSM scenarios. It is sometimes followed by "belly expansion"
• Koonago, where women are shrunk down and endure a variety of torture
• Lolicon, depicts prepubescent or preadolescent girls.
• Maiesiophilia
• Erotic lactation
• Science Fiction, Fantasy and Horror
• Shotacon, the depiction of young boys having intercourse, depicting young boys with older women, known as "straight shota" in western jargon.
• Tentacle sex, the depiction of tentacled creatures or monsters (imaginative or otherwise, also includes alien like creatures) engaging in sex or rape with girls and less often men