Genres
Harem
A relationship-structure convention: one protagonist surrounded by three or more romantically interested partners.
Harem is a relationship-structure convention rather than a plot genre: one protagonist surrounded by three or more romantically interested partners, each member typically built around a distinct archetype. The reverse harem flips the protagonist's gender. In isekai discussion, harem elements are described as part of the standard formula of the Narou style.
Because it is a structure, it composes with anything: comedy, progression fantasy, drama. The craft risk is arithmetic: a large romantic cast multiplies the relationship tracking load.