Born in a remote farming village, a young boy named Heresy has always dreamed of becoming a summoner. His ticket to this future arrives in the form of Happy, a creature he summoned as a child that he considers a sweet and kind-hearted girl. This bond earns him a place at the prestigious Meilleur Royal Summoning Academy, a school typically reserved for the nobility. The central conflict arises from a stark difference in perception: Heresy genuinely sees Happy as cute and endearing, but to everyone else, her appearance is that of a horrifying, grotesque abomination.

Happy’s true form is a nightmarish mass of red and pink flesh, a pulsating lump covered in countless human hands, feet, and screaming faces, with the cries of "kill me" echoing from its form. Heresy, who can communicate with her normally, remains oblivious to the sheer terror his companion inflicts on others. This disconnect is the engine of the story. On his first day, he is forced into a summoning duel with arrogant nobles. When he calls forth Happy, the sight drives his opponents into such profound psychological horror that they are left broken and mentally scarred.

The setting is the academy itself, a fantasy world where summoning magic is the pinnacle of power and social status. Heresy, a commoner and perceived slacker, is immediately labeled an anomaly due to his terrifying summoned beast. Instead of malicious intent, his actions are often mundane, but the mere presence of Happy creates chaos. He unwittingly terrorizes a haughty young lady into submission, who becomes mentally dependent on him to stave off the fear Happy instilled. Heresy interprets her terrified obedience as typical noble eccentricity. The narrative quickly escalates from social chaos to a larger conspiracy, as Heresy is falsely labeled the mastermind behind a sinister plot, forcing him and Happy to confront a genuine crisis to save the academy they unknowingly destabilized. Key narrative arcs include Heresy's struggle for normalcy in a hostile environment, the psychological breakdown of those who see Happy, and the introduction of a second "grotesque beauty" summoned by Heresy, further cementing his reputation as an anomaly.