Gaogao-San is a scientist and inventor who frequently demonstrates his self-created gadgets to the main characters. These inventions, such as a self-feeding spoon and rocket shoes, often malfunction or fail despite his technological focus. He actively joins the younger protagonists on adventures, operating various vehicles and machines to aid their journeys—driving robots, piloting submarines, and flying airplanes to reach diverse locations, serving as both guide and transporter.

The character is known by localized names: Gaogao-San in Japanese media, Dr. Roarson in English-language dubs across the United States and Canada, and Dr. Leo in the Korean version. These regional adaptations preserve his core attributes.

In *Shimajirō to Kujira no Uta*, he helps rescue an injured whale and joins the subsequent underwater quest to find its mother. This expedition involves encounters with ocean creatures and a giant crab, showcasing his logistical support. He also appears in *Shimajiro in Bookland* as part of the ensemble during a quest involving magical paints and storybook realms. His consistent role across the franchise involves providing technological assistance and transportation during group adventures.