In the hot summer, the fireworks festival in Shigeta Town is about to be held. Nasa Ichikawa (voiced by Suzu Hirose), who is studying at a local high school, is not immersed in the happy and peaceful atmosphere. She is about to move to another city with her mother (voiced by Takako Matsu), and her heart is full of loss. In an impromptu swimming competition, Nasa defeated her classmates Norimichi Shimada (voiced by Masaki Suda) and Yusuke Azumi (voiced by Mamoru Miyano). Then she confessed that she liked Yusuke and hoped to play with him during the fireworks festival. However, Yusuke and Norimichi were later involved in a dispute with their friends about "whether the fireworks are round or flat", and everyone agreed to go to a place to witness it that night. Yusuke broke the appointment, and Norimichi, who also secretly liked Nasa, discovered the girl's secrets and thoughts. He blamed his friends for this, and he also longed for time to come back and welcome the original game... This film is adapted from Shunji Iwai's TV series of the same name.