A reverse harem includes three or more characters who potentially show romantic interest in a female protagonist. The sex, gender, or orientation of the harem members is irrelevant as long as they exclusively, or at least primarily, are vying for the affections of the same individual - who may or may not reciprocate towards one, several, or none of these romantic rivals.
Sci-fi, or science fiction, is a speculative genre which builds on imagination. Sci-fi anime ask, "what if things were different?" They explore a new world, whether it's the world of the future or past, a present Earth with a changed history, a land that was previously unknown, or another planet entirely. The genre commonly features humanity's inquisitiveness and innovation, as they grapple with new technologies, new societies, or new frontiers in Outer Space.
These anime delve into the world of competitive Sports, ranging from team-based to individual participants. From Baseball or Basketball, to track and field or combat-based sports, these works focus on the athletes and those around them who show their support.