When manga artist Shin Karino meets his peculiar young neighbor Kotarou Satou, a boy who lives independently at the age of four, he is intrigued by Kotarou's formal speech and mysterious background. Concerned for Kotarou's well-being, Karino keeps a watchful eye on him, leading to a surprising realization of their shared similarities. As Karino and their apartment community embrace Kotarou's quirks, a heartwarming bond forms, potentially offering Kotarou the family he never had.