In the historical backdrop of Nagasaki prefecture's Minami Shimabara city, known for the Shimabara Rebellion, Shirou, a third-year junior high student, cherishes his days with school pals. The tranquil routine is disrupted when Akane, his childhood friend from Tokyo, revisits. Accompanied by another close friend, Tokiya, they meander through familiar streets, evoking nostalgia and stirring deeper emotions. Unexpectedly, a mysterious being named Goron emerges, setting the stage for significant happenings in the city once more.