Tenma Gabriel White graduates Angel College as top of the class and is sent down to earth, along with her classmate Angels to study Humans as a High School student to learn how to better lead them down a righteous path.
At least that is how it should have gone down. Instead Gabriel got addicted to video games and junk food. She even tries to skip school. A failure of an Angel.
Luckliy her Angel-like Demon friend Vignette April Tsukinose helps keeping her on track. Especially by remarking that No-Good Angels get deported back to Heaven. A fate Gabriel wants to avoid because she thinks that her lazy self is her true self, and because Heaven is now too boring for her.
At school Vignette's Demon buddy Satanichia McDowell Kurumizawa causes mischief from time to time. She is egged on by an Angel named Raphiel Ainsworth Shiraha (2nd-best in class after Gabriel) who has slight Sadistic tendencies towards Satanichia.
From time to time Gabriel's shy Angel-underclassmen Tapris Sugarbell Chisaki pays her school a visit.

A lazy Angel, an Angel-like Demon and her pompous Demon-buddy Satanichia and Satanichia sadistic Angel "follower" in one High school.