High school student Kotori is drawn into a fake relationship with Sei, the head of the wealthy and influential Takamiya family. Kotori carries a traumatic past that makes her deeply uneasy around other people, yet she finds herself unable to escape the arrangement after Sei makes a startling proposal: "Let's make a baby." As she is forced to visit Sei every day, she begins to notice that he harbors his own hidden secrets, and the Takamiya family's true motives become increasingly clear. The family is determined to continue its lineage, and Kotori slowly becomes entangled in their calculated schemes. The story follows a lonely girl and a troubled nobleman's son as they navigate a relationship built on false pretenses, gradually uncovering each other's vulnerabilities and the genuine emotions that begin to grow beneath the surface of their arrangement.