You are a pawn in the service of Sirzechs, and you agree to help His Sister Rias Gremory prepare for her upcoming battle against Riser

A down-on-his-luck Necromancer and his dimwitted skeleton companion find a powerful, ancient artifact. But when it accidentally goes off and kills a powerful Paladin, they're forced to flee town. After meeting up with a young woman and her Ogre companion, the Necromancer finds a new purpose and a new life.