Fireworks, Should We See it from the Side or the Bottom?

It is summer in a certain seaside town. As the big fireworks festival approaches, drama is unfolding at the local junior high school. Norimichi's crush Nazuna will soon move away because of her mother's remarriage. Concerned about Nazuna, Norimichi meets with her at the fireworks festival. Nazuna convinces Norimichi to run away with her, but Nazuna's mother finds out and takes her home. Frustrated that he can't do anything, Norimichi hurls away a mysterious round stone that Nazuna had found. Suddenly, time rewinds to earlier in the day, when they were all in school. And Norimichi finds that the same day is repeating over and over again...?!