Alto Goldfield, a student at a magical academy inscribes a magic circle, ends up summoning a powerful demon named Vermeil, makes her his familiar.

Alto Goldfilled, a diligent student at the Ortigia Academy of Magic, aspires to become a powerful sorcerer. But he is unable to become one as, despite his excellent grades and strong commitment to his studies, he fails his summoning class. With the threat of repeating a year hanging over his head, Alto tries following an old, worn-out grimoire in a desperate attempt to resolve his situation. To his surprise, he succeeds and summons a powerful demon named Vermeil. As a sign of gratitude for releasing her, Vermeil agrees to become Alto's familiar, sealing their relationship with a deep kiss. Little does Alto know what else he is capable of and what Vermeil's past hides.—MAL Rewrite

Alto Goldfield is a student at a magical academy who aims to become a master of all magic. However, when he is on the verge of failing a class on summoning magic and in danger of being held back a year, he finds an old summoning grimoire. Following its instructions, he 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 him deeply.—Anime News Network

Rather than take a more sensible approach to salvaging his grades in time for graduation, Alto summons a bit of otherworldly help. Only after does he learn he's bound the legendary she-devil Vermeil into service as his familiar. But while Vermeil is a powerful ally sure to turn his grades around, only a kiss can replenish her magic, and that makes everything go to hell with Alto's jealous childhood friend, Lilia.—Sentai Filmworks

Magic student Alto Goldfield isn't having much luck at summoning, but it's required to advance to the next grade. Then he chances upon an old grimoire and summons a lot more than he anticipated - a very beautiful and naked demon girl named Vermeil. The good news: she's willing to become his familiar. Unfortunately, she also wants to "bond" in another way, live off his mana, and isn't crazy about wearing clothes. This is probably going to get awkward, but in a school where the bullies have dragons, could it hurt to have a familiar who can kick a dragon's tail? Welcome to Demon keeping 101, where, with any luck, Alto will hopefully survive summoning VERMEIL IN GOLD.—Sentai Filmworks