When their mother dies, a junior high school student named Ryota is left to care for his toddler brother Chika and manage their home almost entirely on his own. With his father working long hours and absent for most of the day, the immense pressure of childcare and household duties consumes Ryotas life. Overwhelmed by the workload, he begins neglecting his own health and wellbeing, and with no time left for friends or personal interests, his initial feelings of resentment toward his younger brother soon escalate into genuine murderous thoughts.

The central character is Ryota, a young caregiver whose mental state slowly deteriorates under the strain of his responsibilities. His younger brother Chika is depicted as a toddler whose overly clingy and disruptive behavior wears down Ryotas sanity. As the story progresses, disturbing signs emerge that something is deeply wrong with Chika. Each night, Ryota discovers mysterious bite marks on his own body that his brother has left behind, raising terrifying questions about whether Chika is truly human at all. This suspicion transforms the familys home from a place of domestic hardship into a horrifying trap. The narrative follows Ryota as he becomes consumed by a single obsessive question: how to escape from the entity his brother appears to be.

The series explores the psychological unraveling of its protagonist against the backdrop of a horror mystery. As Ryotas friend Hayato becomes involved in the situation, the truth about Chika begins to surface. The pressures of forced childrearing warp Ryotas mind little by little, leaving readers to question whether he is the source of the problem or the victim of an inhuman situation. The manga ran for a total of 30 chapters, concluding its run in January 2026.