Robotan is a robotic household companion originating from Planet Roboro, constructed by schoolboy Kan-chan (Kanichi Aozora). He integrates into the family as a domestic servant and friend to the children.

His physical design features a head propeller enabling flight ("Robotan Copter") and specialized functions like "Robotan Punch." Bananas serve as his primary energy source, granting him power when consumed in large quantities.

Personality-wise, he exhibits well-intentioned but often clumsy behavior, resulting in mishaps despite his efforts to assist. He develops romantic inclinations, initially toward schoolteacher Umi-sensei, leading to rivalry with another teacher, Uminoyamais, who shares this affection. Later, he becomes attracted to Maririn, an alien robot queen from Roboro who initially aims to destroy Earth, particularly when she appears without her uniform.

His relationships include a persistent rivalry with wealthy neighborhood child Bocchi, who frequently attempts to destroy or enslave him using advanced robots or machines, though these efforts consistently fail; Bocchi's pet parrot, Piiko, occasionally participates. Robotan's bond with his creator Kan-chan remains central, characterized by loyalty and collaborative problem-solving.

Throughout all media iterations—including the original 1966 manga and anime, its 1986 color remake, and related adaptations—Robotan maintains his core role as a comedic domestic helper whose actions drive episodic misadventures. His background as an extraterrestrial robot and ongoing dynamic with rivals and allies remain consistent.