Norimichi Shimada and his friends Yuusuke and Junichi spend a summer day arguing whether a firework looks round from below or flat from the side, and set out to settle it at the town's fireworks festival. Norimichi's classmate Nazuna Oikawa is secretly planning to run away from home that same night, and the outcome of a swimming race decides which boy goes with her. This manga edition tells the story of the 2017 animated film, which also has a novel version.