Gholl is the ruling Demon King in the world of the series, a figure known throughout the land as the most powerful Dark One in history. Despite possessing overwhelming strength, his most defining characteristic is a deeply pacifist nature. This puts him at odds with a significant faction within his own demon army, particularly his younger brother Yuigarde, who leads a pro-war movement and resents Gholl's unwillingness to launch a full-scale conquest of the human territories. Gholl's preference is for diplomacy and coexistence, leading him to make unusual decisions for a being of his stature, such as halting his army's advance to prioritize a personal search for the human Flio, in whom he sees great potential.

His personality is calm, charismatic, and marked by a peculiar obliviousness to the emotions he inspires in others, which contrasts with his immense power. He enjoys gathering information and walking among humans in a disguised form, often using the alias Gholl or Gozal to move through their societies without being recognized. His appearance is not fixed; he can transform into a human guise that allows him to blend in, which he employs during his visits to human lands to recruit Flio and observe other interesting individuals, such as the knight Balirossa, whose lack of reaction to his presence he finds curiously intriguing. Balirossa, in turn, becomes troubled by complicated feelings for the Demon King, which manifest in strange dreams.

Gholl's role in the story is initially that of a potential antagonist, but he quickly subverts this expectation. A major turning point occurs due to a misunderstanding involving a blond hero, which leads Gholl to order an invasion; however, he later calls a retreat to avoid a powerful purification magic. The tension between his pacifism and the warmongering desires of his subordinates culminates in a coup led by his brother Yuigarde. Following this betrayal, Gholl, who deems himself unfit to rule, willingly abdicates the throne. He gives away his possessions and, with his loyal retainer Uliminas, decides to go and live as a freeloader at Flio's home. This decision completes his transition from a ruler on a cosmic chessboard to an eccentric guest in the protagonist's household, where he continues to observe the developing peace between humans and demons.

In terms of abilities, Gholl is considered the strongest Demon King to have ever lived, possessing unparalleled physical and magical power. His strategic mind is also highly developed, allowing him to manage the complex politics of his army with intelligence. Among his specific skills is the ability to change his appearance at will, a power he uses for espionage and to move freely among humans without causing panic. His presence is so commanding that it can cause fear in others, though his relaxed demeanor often unintentionally defuses tension. Despite his title and fearsome capabilities, Gholl's most significant action is his consistent refusal to use his strength for aggression, instead using his intellect and authority to search for a path to peace, ultimately choosing a quiet life with his former targets.