Nagi Umino, a diligent high school student, lives a life defined by academic excellence and quiet routine. His world shifts violently when he discovers a jarring truth: he was switched at birth. His
biological parents, the wealthy and influential Uminos, demand a reunion, while his adoptive parents, the modest and loving Uminos, struggle to process the revelation. To reconcile the two families, an unconventional arrangement is proposed: Nagi must marry Erika Amano, a stunning, social media-savvy girl who was the other infant involved in the hospital mix-up.Erika, however, is a free spirit who fiercely resists the idea of an arranged marriage. She uses her burgeoning influencer career as a shield, desperate to maintain her autonomy and avoid the stifling expectations of her affluent family. Meanwhile, Nagi finds himself hopelessly tethered to his long-standing crush, the brilliant and studious Hiro Segawa. Nagi’s primary motivation becomes a complicated balancing act: he strives to maintain his academic ranking, appease his biological parents, and navigate the volatile, evolving dynamic with Erika, all while trying to win Hiro’s heart.As the narrative unfolds, the situation escalates when the families decide that Nagi and Erika should live together in a shared house to foster their bond. This forced proximity strips away their defenses. What begins as a mutual pact to ignore each other quickly morphs into a complex web of genuine affection, sibling-like bickering, and profound
emotional vulnerability. Erika begins to see Nagi’s hidden depth, while Nagi starts to realize that the girl he once viewed as a pampered nuisance is actually a deeply lonely individual grappling with the pressures of her status.The drama intensifies as the trio—Nagi, Erika, and Hiro—find their lives increasingly intertwined. Secrets about the true nature of the baby swap emerge, suggesting that the "coincidence" may have been a calculated move by the adults. As Nagi uncovers the truth, he must decide whether to follow the path laid out for him by his parents or forge his own destiny. The series evolves into a high-stakes emotional journey, forcing the characters to confront their deepest insecurities, the fragility of their relationships, and the true meaning of family.