Three young country boys are beginning to drift apart as friends. In the summer, they set off to have an adventure in the mountains.

Natsu no pēji

A U.S. helicopter crashes and explodes into a classroom in Okinawa International University. Because of the incident, Yamashiro Ryota thinks back to the blue sky of Okinawa 52 years ago. Ryota is in the 6th grade of Miyamori Elementary School. He plays with his friends Shigeru, Yutaka and other classmates. Hiroko Miyagi is transferred to his class, which makes Ryota happy. Under the blue sky in Okinawa, residents live peacefully. Then on June 30, 1959, a U.S. jet fighter becomes engulfed in flames and crashes into a residential area where Ryota's elementary school is situated. The screaming children flee from the scene. Ryota tries to help Hiroko, but Hiroko is already dead. Now in 2012, Ryota, who is now a widower, lives in his daughter's home. His grandchild Ryuichi is a university student. Ryuichi begins a report on the 1959 fallen U.S. jet fighter incident with his colleagues. The bereaved families in the Miyamori area of Okinawa still suffer. Ryuichi decides to hold a peace and sky concert, but problems occur for Ryuichi.