The story is centered around Kaoru, who is out almost every night playing and singing in front of the train station. At day she sleeps, but every morning she sits by the window of her room to watch a young
surfer, Koji Fujishiro (藤代 孝治 Fujishiro Kōji), played by
Takashi Tsukamoto, who usually waits by a bus stop for his friends before they go
surfing each morning. She develops a crush on the boy, even though she does not know him.
One night, when she is playing as usual by the
train station, she sees Koji pass by. She leaves her guitar and runs after him, running into him and knocking him over when she finally catches up to him by a
train crossing. She then proceeds to clumsily introduce herself in a way that leaves Koji utterly confused and her friend embarrassed. When her friend drags her home, they sit by Kaoru's window while they watch Koji meet his friends by the bus stop. Kaoru explains everything, and her friend notes that she probably goes to the same school as him, and offers to spy on him with a camcorder and find out about him for her.
The next night she sits by the bus stop before going home after singing, and she plays a song there and sings with her eyes closed, and afterwards opens them to find Koji having arrived on his
scooter. Both embarrassed, they start talking and Koji eventually promises to meet her and listen to her sing another night, at the start of the school holidays. When they meet up, another, obnoxious street performer has taken her spot in front of the train station. Koji decides to take her to the city, where after running around seeing the sights, she starts playing in a street square. A substantial crowd gathers to hear her play and sing. After they sit on stairs and watch the ocean. A moment after Koji asks her out.
Their date, however, ends abruptly as the sun breaks through the sky and forces Kaoru to flee back to her home. Koji is soon informed of Kaoru's condition and is set aback. For a period, Kaoru stubbornly refuses to see him, as if her misery would spread to him if they make contact. Remembering her passion to sing, Koji begins working slowly in order to help her compile her own debut single. Her father, out of concern, invites Koji over on night. At dinner, Koji reveals his plans for Kaoru's CD. As they walk home that night, the two begin to talk and Kaoru is slowly brought to tears as she realizes how much Koji truly cares for her. In an attempt to cheer her up, he pinches her cheeks and exclaims: "What a funny face!"
As XP begins to work its effect on Kaoru, she soon loses strength in her hand and is unable to play guitar. She assures Kōji that this will not change anything, that she still has her voice.
In the studio, she asks her family and friends to leave the room. She smiles and tells them that it will be better to wait for the CD to come out before they hear her song. They reluctantly leave the room and Kōji declares his belief that Kaoru will achieve happiness even in her state to an awed family.
After an uncertain time skip, as promised, Koji brings Kaoru to the beach to watch him surf. The suit she had left hanging for years was finally used. By now, it can be assumed that she has lost most feeling in her legs as well, as she is now seated in a wheelchair. She complains that the suit is getting hot. With a painful expression that fades quickly, Kaoru's father tries to convince her that if she takes off the suit, it can't bother her anymore, that she could run around freely. She declines, and with a smile on her face, she says that if she does, she would die. And as of that moment, she would let solidify in her heart her will to live. With that, she struggles to stand up and limps weakly toward Koji. As she walks, she trips over the sand and Koji rushes to catch her. She catches herself at the last minute, revealing that it was a feint and giggles at his surprised face. In an ironic moment, she grabs his cheeks and exclaims happily, "What a funny face!". Koji smiles weakly.
As the movie reaches a close, the scene sweeps over what seemed like a sea of sun flowers. The flowers, it turns out, were the funeral flowers of Kaoru Amane as she was laid to rest. Koji narrates the scene. As his voice fades, a song lifts. Koji, Kaoru's friends, and her family listen happily to radios as Kaoru's CD is finally released. A flashback that was never revealed finally makes its appearance, featuring Kaoru singing the song with passion. So much so that tears begin to fill her eyes as she finishes. The studio applauds her finish as she sniffs and laughs. It is never revealed whether her tears were of joy, conclusion, or realization that her life would end soon. The final scene features a matured Koji who is with his friends on the beach. With a surfboard in hand, rushing towards the waves, his mind replays the voice of Kaoru Amane, and her song to the sun.
