Varuga originates as an ancient demon-dragon entity, bound long ago by an ancestor of the Rimzbel royal family and sealed beneath their castle for generations. He resembles a large, green, Godzilla-like dinosaur with piercing yellow eyes, capable of unleashing immense destruction through physical attacks and fiery breath. During an invasion, Princess Luna summons him, triggering a fusion that physically attaches her lower body to his forehead. This bond positions Luna as his "brain," granting her control over his movements while directing his actions. Even outside combat, the connection manifests visibly as a reptilian tail extending from Luna.

His presence enables Rimzbel's defense against invaders, though the fusion causes Luna significant personal embarrassment. Following the kidnapping of Luna's younger sister, he accompanies her on a journey to confront the demon-possessed Emperor of Dambas and rescue her sibling. Throughout this quest, Varuga demonstrates intelligence through direct verbal communication with Luna, protective instincts toward her family, and awareness of a greater threat posed by resurgent extra-dimensional evils linked to his own ancient origins. His size fluctuates situationally, shrinking when not actively engaged in combat. Varuga's history and motives remain centered on fulfilling his ancestral pact with the royal bloodline through his direct partnership with Luna.