Sada Seiji is an earnest and admired high school teacher, popular with both his students and fellow faculty. One night while patrolling the school grounds due to recent incidents, he witnesses a shadowy figure attack a female student with a knife. When he tries to intervene, Sada is also fatally stabbed and dies at the scene.

Instead of dying, Sada regains consciousness lying naked and strapped to a cold examination table in an unknown laboratory. He is greeted by Mamiya, a scientist who explains that he has resurrected Sada by injecting him with a proprietary cellular formula. However, Sada quickly realizes that cheating death has come at a terrible cost. He is no longer fully human and now exists as a zombie. To prevent his body from decaying, he must survive by consuming human blood and viscera. He is now completely dependent on Mamiya, who is staking his entire career on this groundbreaking but monstrous experiment.

The story is set primarily within the confines of Mamiya's isolated laboratory, where the two men develop a deeply codependent and morally fraught relationship. Sada, a man of strong conscience, struggles to reconcile his new existence with the horrific necessity of killing to eat. Mamiya initially treats Sada as a research subject, conducting painful experiments and tests without anesthesia, maintaining a cold and detached demeanor. However, Sada’s persistent decency and attempts to treat Mamiya as a person gradually begin to chip away at the scientist’s isolated and rigidly scientific worldview. The narrative explores dark themes of morality, survival, and the gradual development of an intimate and complex bond between a gay man forced into an inhuman state and a potentially neurodivergent or asexual loner whose concept of affection has been warped by trauma and obsession.

Notable narrative arcs include Sada's initial horror and physical torture as he endures Mamiya's experiments and comes to terms with his cannibalistic diet. The pair later develop a grim routine where they discuss the logistics of kidnapping and murder at the dinner table, with Sada preferring to target criminals to ease his conscience while Mamiya remains detached. A significant turning point involves a revenge scheme tied to Mamiya's past, which brings his hidden vulnerabilities to the surface and forces Sada to confront his growing feelings for his captor. The story culminates in a tragic and bittersweet conclusion, as the unique and impossible nature of their bond reaches its inevitable, heartbreaking endpoint.