Seita is a musician living in Tokyo who is facing a severe creative block. He disappears, and his sister, Azumi, a young deaf girl, finds him in the mountain house where they spent their childhood. Isolated, he tries to get back to composing and begins recording birdsong for inspiration. The two brothers start living together there. Azumi's presence, movements and sounds, which initially irritate Seita, help to unlock the boy's creativity over time. However, the artist becomes bothered again when Taichi, Azumi's boyfriend, decides to pay a visit.
Naoko meets Yusuke while staying on an island for medical treatment. Yusuke's graceful athletic figure captivates her eyes and she falls in love with him. But their relationship is soon broken after Yusuke's father dies while trying to save Naoko from drowning. The memory of Yusuke leads Naoko to the track, and six years later, they meet each other again at a Marathon competition. Naoko decides to become a manager to help Yusuke, a gifted runner, and they embark on training together to heal their sorrows from the past.