In the near-future, the world's energy problems have been solved thanks to a scientific invention known as the Manifestation Engine which creates energy from the sky. On the island of Izu Oshima, Akane Isshiki is living a simple life with her sister, Momo, and her grandfather and creator of the engine, Kenjirou. As Akane eagerly awaits the arrival of her classmate, Aoi Futaba, who is traveling to the nearby Blue Island for treatment, she and Momo hear an explosion coming from their home and discover that Kenjirou has somehow switched bodies with a stuffed otter doll as the result of an experiment...