The story follows , a young man who has lived his entire life as the only human on the machine-inhabited planet Granbell , a deserted theme park. His isolated world changes when Rebecca Bluegarden , a "B-Cuber" (content creator), and her robotic cat companion Happy arrive to film a video.

Shiki uses his Gravity Ether Gear powers—inherited from his adoptive grandfather, the mechanical "Demon King" Ziggy—to defeat the robotic Castellan and rescue his new friends.

Shortly after they meet, the planet's robots suddenly turn "evil," tying up Rebecca and claiming they want revenge against humanity.

As Shiki, Rebecca, and Happy blast off into the Sakura Cosmos , it is revealed the robots' rebellion was a staged act. Knowing their batteries were dying, the machines pretended to be villains to force Shiki to leave the planet so he wouldn't be left alone after they deactivated. Core Themes & Character Dynamics