Cosmo, alternatively called Tanpei in certain regions, is a 13-year-old hero defined by his hot-blooded courage and relentless drive. He dons a signature blue jumpsuit and helmet, serving as both a skilled mechanic and the primary operator of a time-traveling machine. His technical brilliance shines through inventions like Chorobo, a compact robot companion equipped with extendable limbs, a flamethrower, and an electric shock mechanism activated by a winding key on its back. He routinely repairs and maintains the time machine after battles, showcasing his knack for quick thinking in high-stakes situations.

Though details of his past are sparse, he stands as a loyal assistant to an eccentric scientist who vanished mid-experiment. This disappearance thrusts Cosmo into leading a team—comprising the scientist’s granddaughter, Junko, and Chorobo—to find his mentor and secure the Dynamond, a potent gemstone sought by rival factions. Their dynamic blends mutual respect with flickers of romance, though his impulsive decisions and occasional panic in trivial moments stir challenges during their quest.

His unwavering moral compass clashes with the primary antagonists’ self-serving agendas. Despite occasional recklessness, he relentlessly focuses on aiding those in need and resolving disputes, even when his overconfidence backfires. In combat, he combines hand-to-hand prowess with tactical deployments of the time machine’s insect-inspired armaments: rotary saws, missile launchers, and flight systems mimicking insect physiology.

Expanded media, like the 1993–1994 OVA *Royal Revival*, place him alongside characters from connected franchises without altering his core traits. His design—particularly the iconic blue attire and valiant demeanor—became a blueprint for future protagonists within the franchise. Cross-media homages include a music video featuring a boyband member emulating his costume and combat techniques.