A loved one died. Momo, a high school student who lost her best friend Sayo, who had been with her since elementary school, in a sudden accident.

In despair, she reunites with Sayo's younger brother, Keichiro, at the funeral for the first time in eight years. The secret base in the residential area, the ferris wheel dyed in twilight, and a candy shop they frequently visited. Momo and Keichiro trace the places from their memories as if to regain the fun memories of their childhood. Looking for the view of summer which was supposed to be spent with her best friend --with his sister-- with Sayo. A heartrending blue summer graffiti spun by the boys and girls who lost their loved ones.

Includes 1 epilogue and 5 bonus chapters.