16-year-old super-studier Nagi Umino, second-year student at the Megurogawa Academy high school, was switched at birth. On his way to a dinner to meet his birth parents, he accidentally meets the brash, outspoken, Erika Amano, who is determined to make Nagi her fake boyfriend as she never wants to actually marry. But once Nagi makes it to dinner, he finds his parents have decided to resolve the hospital switch by conveniently having him marry the daughter his birth parents raised…who turns out to be none other than Erika herself!
Nagi’s real brother, Sokke, is moving behind the scenes, and he declares his goal during a surprise visit to Sachi… Meanwhile, Nagi and Hiro spend the night at the Ama-Umi House, and their relationship will progress under the shared roof… As the hunt for Sosuke gets serious, Nagi is feeling competitive, and his savior arrives in the form of Ai-chan. Their first meeting is finally revealed… Finally, Erika pursues the mysterious “S” account on social media. Amid the growing tension, everyone’s fate will take a shocking turn!!