Tsuneo Suzukawa, a university student and part-time store employee in Osaka, Satoshi Tsumabuki rescues the disabled Josee Chizuru Ikewaki when she accidentally pushes her wheelchair down a steep road. Josee’s grandmother, Chizu, Eiko Shinya, invites him to stay the night, and Tsuneo becomes Josee’s caretaker. At first, Josee acts selfishly, but their relationship begins to deepen as they spend quiet days together, especially along the shoreline where the sea mirrors the slow, tentative growth of their bond. The pair share moments that hint at a future beyond their respective worlds, and Josee’s friend Kana Kishimoto, Juri Ueno, helps her find a place at the library, where she is hired by Kanae and starts to contribute in a new, creative way.
As Tsuneo earns a scholarship and receives an offer to study in Mexico, he keeps the next steps of his life to himself, not yet ready to reveal the changing tides ahead to Josee. The couple’s fragile equilibrium is shaken when Chizu dies of a heart attack, leaving Josee with the sense of abandonment and the looming question of what life will look like without the familiar, nurturing presence of her grandmother. Two coworkers urge Josee to “redeem herself and set Tsuneo free,” a sentiment delivered by Mai Ninomiya in a way that unsettles their already delicate balance.
Josee shifts again, moving toward an office role rather than pursuing art, and a rift forms after a heated argument at the beach. In a cruel twist of fate, Josee’s wheelchair becomes stuck in the road, and Tsuneo is involved in a car accident that leaves him with a broken right leg and two months in the hospital. When the professor informs Tsuneo that another student will replace him for school and travel, he steps back from his dream and begins to wrestle with letting Josee go even as he longs to stay.
During recovery, Mai’s words echo in Josee’s mind, nudging her toward a path where she can support Tsuneo from a distance. Yet Josee’s artistic spark returns, and she resumes painting, finding strength in her own identity as an artist. Tsuneo’s friend Hayato Matsūra accompanies him from the hospital to the library, where Josee reads a story she has drawn—a tale titled The Mermaid and the Radiant Wings, an allegory for their relationship. Reading aloud to the children rekindles Tsuneo’s resolve to push through physical therapy, and he begins walking again with renewed determination. He asks Josee to be there before his discharge, but she replies that she will be happy for him even if she cannot be there in the same way.
When Tsuneo is discharged and returns to an empty house, Josee is gone. Friends search the city while Tsuneo follows the trail of wheelchair tracks in the snow from the zoo, where Josee once watched a tiger. A careless passerby knocks the wheelchair into a snowy road, and Josee tumbles, only to be saved by Tsuneo once again, in the same life-saving moment that marked their first meeting. In that intimate, quiet reunion, they confess their feelings and lay out a shared future: Josee reveals her dream of becoming a storybook illustrator, and Tsuneo vows to stay by her side. Josee asks about Mexico, and Tsuneo says he will return home because he loves her; she echoes the same sentiment, and they embrace.
Tsuneo eventually travels to Mexico, while Josee leaves the house as demolition begins on her old life. The following year, Tsuneo returns to Japan and continues spending his days with Josee, embracing a future that remains uncertain but is defined by mutual commitment, growth, and the art they nurture together.
