Popular romance novelist Rakumoto Ai reluctantly visits a remote island for research. Greeted by Muto Kaishin in a yellow taxi, Ai initially wants to leave but slowly warms up to the island’s beauty and Kaishin’s constant care and teasing.

Kaishin takes Ai on a motorcycle tour around the island, showing his gentle and caring side. Although Ai complains often, he opens up and they share their pasts and feelings. Meanwhile, Ai’s secretary Ogura Fumi is forced to help actress Himeka Ui at her home.

After an intense night together, Kaishin and Ai’s relationship quickly deepens. Kaishin stays busy guiding tours on the island, while Ai focuses on writing. One day, Kaishin takes Ai diving, but Ai is triggered by childhood memories. Meanwhile, Himeka’s scandal grows, and she starts a “fake lover” relationship with Fumi.

Ai struggles with writer’s block and anxiety, and Kaishin takes him out for fresh air. They arrive at the sea, glowing with candlelight and starlight, where kisses and embraces bring them closer. Meanwhile, Himeka and Fumi use their “fake lover” relationship to quell rumors, exchanging bickering words but gradually forming a unique bond.

Kaishin holds a marine conservation seminar, showing his deep love and commitment to the ocean. After the event, the pair visit Kaishin’s home, share their feelings, and ignite their passion. The next day, Ai receives an urgent work call and rushes back to Tokyo. Reluctant to part, Ai asks if Kaishin can come to Tokyo with him.

Ai brings Kaishin into his home, marking the start of their cohabitation, but secretary Fumi distrusts Kaishin from the beginning. The two sign a contract that defines their bond as only transactional, strictly forbidding love. Yet, Kaishin gradually blends into Ai’s life, and his straightforward affection keeps breaking down Ai’s defenses.

Kaishin’s heartfelt cooking warms the lonely Ai, giving him the courage to open up about the abuse he suffered as a child. That night, the two share a passionate kiss, crossing both physical and emotional boundaries in an intense, intimate moment. Meanwhile, Himika’s pursuit of Fumi grows bolder…

Before Ai’s book signing event, his cousin suddenly shows up and causes a series of misunderstandings. But a darker shadow looms — Ai’s father returns, investigating Kaishin’s past and trying to put an end to their relationship.

Himeka admits to Ai that she has feelings for Fumi but cannot bring herself to confess. Ai warns her not to confuse fiction with reality, but Himeka turns the tables on her by pointing out her own feelings toward Kaishin. Ai’s father reappears, triggering traumatic memories of past abuse.

For the past year, Ai and Kaishin have been navigating a long-distance relationship, traveling between the city and the island. For Ai, the island where Kaishin lives has truly become home. Meanwhile, Himeka and Fumi remain caught between pursuit and avoidance. As they visit Ai and Kaishin on the island, will the passion of the sea bring their feelings closer together?

On the island trip, Ai and Kaishin’s relationship enters a steady phase, filled with tender and intimate moments. Inspired by their love, Himeka and Fumi grow closer, and that night, with the courage of wine, Fumi finally confesses.