Nagisa, a 26-year-old woman desperate to change her stagnant life, falls victim to a scam while traveling and is rescued by Soji Sazanami, the powerful young leader of the Sazanami clan. In exchange for her future safety and security, Nagisa agrees to a sudden arrangement to act as his wife. However, she quickly realizes the perils of Soji's world when she is used as a wager in a high-stakes poker game.
After Sazanami defends her honor, Nagisa reflects on the profound impact he has had on her during her time abroad. Knowing their time together is coming to an end, she makes a bold request for Sazanami to be her first lover. The two share a passionate night of intimacy and confession before Nagisa must rush to catch her flight home.
Nagisa's attempt at a quiet life is shattered when Sazanami reappears as the new CEO of her company. He forces her into a provocative three-month wager, betting that she will inevitably fall in love with him. Now bound to him both professionally and personally, Nagisa must struggle to maintain her boundaries against Sazanami's seductive and controlling advances.
Nagisa struggles to maintain her boundaries with Sazanami, but the Boss uses his authority to corner her for a private meeting in his office. After confessing his intense desire to make her his wife, Sazanami engages in a risky and passionate encounter with Nagisa right in the workplace, leaving her overwhelmed by his relentless pursuit.
After her childhood friend warns her about Sazanami's dangerous reputation as a Yakuza leader, Nagisa is subjected to Sazanami's intense possessiveness. Following a passionate encounter fueled by his jealousy, Nagisa asserts her independence and her right to choose who she loves.
Nagisa is targeted by an enemy of Sazanami who intends to use her as leverage to settle a past grudge. Sazanami arrives just in time to rescue her, sustaining injuries in the process. As Nagisa tends to his wounds, the tension between them escalates into an intimate encounter fueled by Sazanami's possessive desire to ensure she remains untouched by others.
Sazanami and Nagisa share a moment of intense intimacy, during which Sazanami reflects on his unwavering devotion to her. The narrative shifts to a poignant flashback of their first meeting, revealing the compassionate act that first connected them and the vulnerability that drew Sazanami to Nagisa.
Nagisa discovers that Soushi has secretly cherished a handkerchief of hers for years, revealing his long-standing devotion and longing. After sharing a moment of profound emotional and physical intimacy, the two reaffirm their love and desire to be together for the rest of their lives. To further strengthen their bond, Soushi leverages his position as CEO to arrange a sudden "business trip" to a hot spring, effectively planning a romantic getaway for the couple.