Gorōzaemon Sanmoto is a significant figure in the world of Tonari no Yōkai-san, recognized as one of the twelve Demon Kings residing in the demon realm. Despite this fearsome title, he is not a figure of terror but rather an influential and charismatic leader who serves as a representative for the yōkai of Japan. He carefully manages his public image, often appearing in the human world under the guise of a well-dressed, besuited man with blonde hair and a goatee, a form he uses to run a successful entertainment agency. In this capacity, he is a celebrity who even makes television appearances, presenting himself as a successful and modern figure. However, this human-like appearance belies his true nature as a being of immense power; his authentic form is said to be a colossal, hairy beast of enormous size, comparable to the volume of one and a half Tokyo Domes.

His motivations are largely centered on the guidance and protection of the yōkai community. Sanmoto holds a position of significant authority and uses it to nurture and support other yōkai, especially those who are newly reborn. He demonstrates a particular interest in the main character Buchio, the young cat yōkai, whom he offers tutelage and life guidance, recognizing the potential in the newly transformed Nekomata. This mentorship highlights a key aspect of his personality: he is not a distant or tyrannical ruler but a proactive and invested leader who takes an active role in the development of his kind. His influence is also felt through his direct subordinates, such as the nekomata Suzu Sakaki, who works as a chief manager in his agency and shares his desire to help others, having been saved by his words in her own past.

Within the broader narrative, Sanmoto’s role is that of a high-ranking authority figure who operates on a different level from the local yōkai of the rural town of Fuchigamori. He represents the larger, more organized political and social structure of the yōkai and demon world that exists parallel to human society. His presence connects the small-town story to a much wider and more complex universe. While he may not be a constant physical presence in the daily lives of characters like Buchio or the crow tengu Jiro, his actions and the systems he oversees have a direct impact. The entertainment company he runs in Tokyo serves as a modern and unconventional base for his operations, further emphasizing the series' theme of old magical beings adapting to and integrating with contemporary society.

A notable aspect of Sanmoto’s character is his unique ability to be in multiple places simultaneously. He can place clones, or aspects of himself, at various points around the world, allowing him to exist in multiple locations at the same time. This power not only speaks to his immense magical capabilities but also explains how a single "Demon King" can effectively oversee a vast domain, manage a media company, and still appear to guide individual yōkai like Buchio. This ability contributes to his enigmatic and almost omnipresent nature, solidifying his status as a powerful yet benevolent force within the story’s universe.