The protagonist, tormented by an insatiable desire, discovers a hypnosis app on his smartphone. Initially repulsed by its sinister nature, his curiosity leads him to test it on his sister, transforming her into a lifeless doll. Though he immediately uninstalls the app, it reappears, forcing him to hide it. Driven by a growing obsession, he eventually succumbs to temptation and uses the app on a girl he admires from afar.
He lures her to an empty classroom and activates the app, rendering her a compliant "living doll." This marks the beginning of his descent. He experiments with the app's commands, discovering her obedience to simple instructions in Japanese, but her confusion with English and German. He commands her to sing, and she unexpectedly performs a lullaby, which triggers a painful realization: she has a younger sister, and the lullaby is meant for her. Overwhelmed by guilt for corrupting such a pure act with his own desires, he flees and attempts to atone by being unusually kind to his own sister.
Despite his remorse, the protagonist finds himself drawn back to the girl. He continues to use the app, indulging in increasingly depraved acts. He forces her to sit on his cushion, an act he finds both shameful and intoxicating, and later steals the cushion, cherishing its scent. He becomes consumed by the desire to know her physically, using the app to strip her and then employing a body composition scale to learn every detail of her physique. He even records her voice, driven by a perverse longing to hear her express affection, only to discover the recording was lost due to insufficient storage. Each transgression deepens his despair and self-loathing, yet he remains enslaved by his desires, unable to stop himself from further exploiting the girl, whom he views as an object for his gratification. His actions escalate to a point where he forces her to engage in sexual acts, further solidifying his transformation into a "monster." He is trapped in a cycle of guilt and compulsion, unable to escape the allure of the power the app grants him and the depraved pleasure he derives from it.
