Young teenage girl Roue lives a peaceful life with her “uncle“, a droid named Zett. She spends her days exploring the ruins of the old world, destroyed by World War III two hundred years ago. During one of those explorations, she finds a strange cylindrical droid who calls himself Chrome, who for some reason doesn’t have a “base program“, which determines a droid’s main purpose. Chrome may have to find that purpose himself in his new life with Roue and Zett…

In a ruined world, a human girl, Roue, and a gear Zett, live a humble life. Then one day, they encounter a mysterious new gear, Chrome... Now all three of them live together like a family, but then…