Harem (genre)

Harem (ハーレムもの, hāremumono; "from harem"^?) in anime and manga is an emphasis on polygamous or love triangle relationships characterized by a protagonist surrounded amorously by three or more members of either the same and/or opposing gender, sex, and/or love interests. When it is a yuri or male-hetero oriented harem series, the polygynous relationship is informally referred to as a female harem or seraglios. When it is a yaoi or female-hetero oriented harem series, the polyandrous relationship is informally referred to as a male harem, reverse harem, or gyaku hāremu (ハーレム^?).

The word derives from Harem, which was a term used to refer to the most private rooms of a household in the Islamic world, especially among the upper class where only Women and close relatives were permitted inside.

Because romance is rarely the main focus of an entire series, a harem structure is ambiguous. The most distinguishable trait is the group of polyamorous females and/or males who accompany the protagonist; in some instances cohabitate with the protagonist. While intimacy is just about customary, it is never necessary. When it is present, it is always a minimum of three supporting characters who express romantic interest in the protagonist.

...
Wikipedia