Yuri Kashiwaga was once known as a genius pianist. One day, she returns to her hometown in Goto Islands from Tokyo. There, she begins to work as a temporary teacher at a middle school and advisor for the school chorus. The chorus aims to take part at a competition. Yuri gives the members of the chorus members an assignment. She instructs them to write a letter with the title of “To myself 15 years later.” The 15-year-old boys and girls write about their secrets and worries.

Teenage Mutsuko comes to Tokyo for work but ends up at a repair shop. She befriends the owner's family. Neighbors Hiromi, writer Chagawa with admirer Junnosuke strive alongside them in postwar Tokyo's evolution.