Norimichi Shimada and his friends plan to settle the debate on whether fireworks appear round or flat from a certain angle during summer. To prove their theory, they devise a plan to witness the fireworks showcase at Moshimo Festival. However, things take a complicated turn when a classmate named Nazuna Oikawa asks Norimichi to run away with her. Their escape plan fails but a strange sphere owned by Nazuna presents them with a chance to unite once again.