Monga is a teleporting space creature and one of 21 Emon's primary companions throughout the series. As an alien, he uses his power of instantaneous teleportation to facilitate the group's interstellar travel and solve problems during their adventures.

Despite his extraterrestrial origins, Monga communicates primarily in Japanese, enabling seamless interaction with human characters. His physical appearance features a distinctive color-changing trait linked to his emotional states, with yellow specifically indicating happiness. Monga exhibits an extreme omnivorous diet, consuming a wide variety of materials beyond conventional food, classified as a "fantastic diet requirement" inherent to his species.

He forms part of the core trio alongside 21 Emon and the robot Gonsuke, frequently assisting with operations at the Tsuzure Inn family hotel while participating in space exploration. Monga appears consistently across all official media adaptations, including the original manga serialization (1968-1969), the 1981 film *21 Emon: Uchū e Irasshai!*, the 39-episode television series (1991-1992), and the 1992 short film *21 Emon: Soraike! Hadashi no Princess*. His role extends to crossover appearances, notably in the special *21 Emon & Doraemon: Welcome to Hotel Tsunesha*.