You’re a student at a magical academy who aims to become a master of all magic. However, when you’re on the verge of failing a class on summoning magic and in danger of being held back a year, you find an old summoning grimoire. Following its instructions, you inscribes a magic circle, and ends up summoning a powerful demon named Vermeil, who was sealed long ago, and makes her his familiar. However, the voluptuous Vermeil occassionally requires magical energy from Alto, which she claims by kissing you deeply.