Angel Sanctuary is a manga written and illustrated by Kaori Yuki from 1995 to 2001, which in 2000 was adapted into an OVA of 3 episodes directed by Kiyoko Sayama.
Setsuma Mute is the reincarnation of a fallen angel named Alexiel, who was punished by God separating his soul from his body; his body was turned into glass and soul condemned to die as a human repeatedly. Today heaven and hell in difficult situations, this is where Alexiel must fight for the soul of his sister Sara (who is also in love) and to explain that he is an angel so they can live together as humans.