Arata Kasuga is “cursed” with something known as the Collapse Phenomenon which has the capability of destroying the world and there are people after him for this power. Some want to be able to abuse him power and there are others who want to kill him so this power doesn’t fall in the wrong hands. The ones looking to kill him are the girls of Biblia Academy. The girls each have their own powers based on the seven deadly sins so they are definitely capable of taking him out. What Arata doesn’t know is that the girls of the Academy may be his only hope of understanding the phenomenon and saving his cousin who seems to have disappeared because of it.
What sets this one apart from others is the characters. Arata is not your usual weak, lame main character who is oblivious to what’s going on. He’s perverted but not in an over the top way and you know he likes what he sees but he’s not going around trying to peek at panties and things like that. The girls also, for the most part, try to have their way with him. It’s more of a 2 way harem vs the usual harems where it’s usually one sided.
Trinity Seven may be “just another harem” anime but it’s different enough that it stands out. If you’re looking for a funny harem anime then this one is for you. There is also a movie which takes place after the series but follows the same trajectory.