A Devil goes by the name of Sebastian has his life turned around as he was killed and revived by Rias to make him a slave to her, thanks to what Rias did Sebastian will have to get stronger for her to fight against so many powerful foes who wants Sebastian dead, now he will change his life around all thanks to the one he will soon fall in love with.

Zazuki Kurosuki is the youngest person to ever hold a position on the Magus Conclave and now Sirzechs has asked for his help in preventing from another War of the Three Factions. OC centric and OCXHarem since it is Highschool DxD.