Shiki, the main protagonist of the story, is a friendly yet socially awkward boy who's the sole human denizen of the Granbell Kingdom, a fantasy theme park on the planet Granbell inhabited by robots. He possesses an ability called Ether Gear, which is inherited from the park's animatronic Demon King, granting its user powers akin to those of a machine; Shiki uses a variation known as "Satan Gravity" that allows him to alter and redirect his own personal gravity. Encouraged by his artificial family to go out and make some real friends, he gets swept up on a journey with Rebecca to see new worlds across the cosmos.