The Apprentice of a Demon

Louise had finally snapped. The taunts and the disappointment was too much. She cut off her emotions as to try to be sane, but sometimes to be sane, there must be someone insane with you. And it has to be her bad luck to summon a sword that calls himself Satan. But its her good luck that he'll take her as an apprentice. There's only thing she has to sacrifice. Her Humanity.