Dr. Tenma builds the robot Tobio to replace the son he lost, then abandons him when the copy refuses to grow up like a real child. Rescued by robot-rights advocate Professor Ochanomizu and renamed Astro, the boy is fitted with seven built-in abilities: rocket-powered flight, super strength, and searchlight eyes among them. He grows up in a near-future Tokyo where humans and robots share the streets uneasily. Alongside his robot sister Uran, Astro takes on threats no human police force can handle, standing as proof that a robot can choose to protect the people who once discarded him.