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.
Although the yaoi genre is also called Boys' Love (commonly abbreviated as BL), the characters may be of any age above puberty, including adults.
Works featuring prepubescent boys are labelled shotacon and seen as a distinct genre.
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.
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 possibility of switching roles is often a source of playful teasing and sexual excitement for the characters, indicating an interest among many genre authors in exploring the "performative nature" of the roles.
Aleardo Zanghellini suggests that the martial arts terms have special significance to a Japanese audience, as an archetype of the gay male relationship in Japan includes same-sex love between samurai and their companions.
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.
In the 1980s, the genre was presented in an anime format for the first time, including the works Patalliro!
(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.