This is a sub-genre of the romantic-comedy genre. To qualify, you have to have a single, dateless, nice guy who suddenly finds himself surrounded by a bunch of hot girls/women who are interested or attracted to him to varying degrees. The male lead may also live with many of these girls.
The nature of a story line are often defined by both the age and issues that the main character has to confront. A student in college would approach a situation very differently than someone in middle-school. This tag is intended suggest that the story is more mature (or perhaps less hormonally driven and spastic) in its nature. Aa! Megami-sama! OVA and Ai Yori Aoshi are both very good examples as to the fun adventures of a college-aged students.
