Theodore Miller, despite his vast knowledge of magic, struggles with its practical application. On the verge of failing at Berghen Academy, he stumbles upon a peculiar grimoire named 'Gluttony' that transforms into a magic-devouring entity attached to his hand. As Gluttony consumes magical tomes and objects, Theo gains unprecedented power, propelling him to the top student position at the academy. Despite the looming danger of being devoured by this insatiable parasite, Theo sees this as his opportunity to truly master the art of wizardry.