On the fictional Okinawan island of Yonaki Island, Tomoyose Akio runs a small general store inherited from his grandmother. He lives quietly with his dog, Kafu, whose name in the local dialect means "good news" or "happiness." Akio's father died in a fishing accident when he was young, and his mother disappeared after the stillbirth of his younger brother. At age thirty-five, during a group trip to a shrine on a northern island, Akio writes a half‑joking message on an ema: "Won't you marry me? I'll make you happy," signing it with his name and address. Months later, a letter arrives from a woman named Sachi, who says she saw the ema and has decided to come to Yonaki Island to become his bride. Akio is startled but intrigued. A few days later, Sachi appears under a banyan tree near his home, a beautiful woman in a white dress. She moves into his house, and an awkward but warm co‑habitation begins.

Sachi quickly becomes the talk of the island. Despite being clumsy at housework, she helps in the shop and charms the locals. Akio gradually falls for her, but his shyness and past traumas make him hesitant. Meanwhile, the island faces a resort development plan pushed by Akio's childhood friend Teruya Shun'ichi, who works for a large development corporation. Shun'ichi pressures Akio to sell his land, and the conflict divides the small community. Akio's only allies are the elderly yuta (spiritual medium) who lives behind his house, and a diving shop owner. As opposition crumbles, Shun'ichi hints that Sachi might be an actress hired to persuade Akio to agree to the development. Believing this, Akio gives Sachi money and sends her away in anger and hurt.

After Sachi leaves, Akio learns from another childhood friend, Arakagi Wataru, that the actress Shun'ichi hired never came to the island. Sachi was not involved. A letter from Sachi arrives, revealing the truth: her father had once lived with Akio's mother for a short time, and as a child she heard stories about Akio. Years later, while working as a waitress at a hotel on the same northern island, she found his ema and decided to meet him, not as a scheme but out of genuine feeling. The letter ends with gratitude for their time together and a confession that she truly loved him. Realizing his mistake, Akio vows to search for her across the country and bring her back to the island where Kafu waits.

The story weaves themes of loneliness, the courage to trust, and the meaning of "Kafu" — the good news that comes not from waiting passively but from taking action. It also depicts the tension between preserving traditional island life and the pressures of modernization, as seen through the development conflict. Akio's emotional journey from a cautious, wounded man to someone willing to risk everything for love forms the core of the narrative, while the vivid Okinawan setting — the sea, the banyan tree, the shrine — grounds the romance in a sense of place and possibility.