A young piano prodigy, Yuri Kashiwagi, returns to her hometown after several years and joins a middle school to mentor the choir group.

In a small fishing village, a gloomy middle school student named Kai meets a mermaid named Lu.

Sasaki Ryohei (Yamada Ryosuke), the second son of the Sasaki family, is a high school student who lives in Shimane. He has just been chosen to be the vice captain of the youth soccer club. Setting his sights on participating in the prefectural championship, Ryohei practices every day with his buddies. One day, Ryohei has a severe headache and is brought to the hospital. Ryohei is diagnosed with an acute brain tumor from the test results. The family is told by the doctor that Ryohei will not live long. However, Ryohei musters the strength to say, "I will win. I will beat the illness. " Given a push by his words, the Sasakis try to stay positive.