In the late 1970s going into the 1980s, women and girls in the dōjinshi (fan fiction) markets of Japan started to produce sexualized parodies of popular shōnen (boy's) anime and manga stories in which the male characters were recast as gay lovers.
By the end of the 1970s, magazines devoted to the nascent genre started to appear, and in the 1990s the wasei-eigo term boys' love or BL would be invented and would become the dominant term used for the genre in Japan.
(1982) which showed a romance between two supporting characters, an adaptation of Kaze to Ki no Uta (1987) and Earthian (1989), released in the original video animation (home video) format.
The use of yaoi to denote those works with explicit scenes sometimes clashes with use of the word to describe the genre as a whole, creating confusion between Japanese and Western writers or between Western fans who insist on proper usage of the Japanese terms and those who use the Westernized versions.
Yaoi can also be used by Western fans as a label for anime or manga-based slash fiction.
The term shōnen-ai (boy love) originally connoted ephebophilia or pederasty in Japan, but from the early 1970s to the late 1980s, was used to describe a new genre of shōjo manga, primarily produced by the Year 24 Group of women authors, about beautiful boys in love.
Works featuring prepubescent boys are labelled shotacon and seen as a distinct genre.
The tachi partner is conceptualized as the member of the relationship who pursues the more passive partner, the latter of whom is referred to as the neko.
Characteristics of shōnen-ai include exoticism, often taking place in Europe, Jeffrey Angles particularly notes Moto Hagio's The Heart of Thomas (1974) and Keiko Takemiya's Kaze to Ki no Uta (1976-1984) as being groundbreaking, noting their portrayal of intense friendship between males, including jealousy and desire.
The word was originally used to describe an author's distinctive style, for example, the styles of Yukio Mishima and Jun'ichirō Tanizaki.
Another way the seme and uke characters are shown is through who is dominant in the relationship - a character can take the uke role even if he is not presented as feminine, simply by being juxtaposed against and pursued by a more dominant, more masculine, character.
Although not the same, a yaoi construct similar to seme and uke is the concept of tachi and neko.