Zirconia is the chief enforcer and ringmaster of the Dead Moon Circus, acting under Queen Nehelenia's direct command. Created from Nehelenia's deep fears of aging and fading beauty, she embodies those rejected aspects. Her existence remains intrinsically linked to Nehelenia, whom she serves with unwavering loyalty from within the circus. She presents as an elderly figure with lavender, wrinkled skin, typically concealed by long dark purple robes. A scowling face-like shadow adorns her cloak, capable of projecting Nehelenia's image. Zirconia is crowned by a white horned helmet bearing the Dead Moon Circus symbol and wields a tall staff topped with her pet eyeball, Zircon, which serves as her spy. Her demeanor is stern and joyless; she frequently berates subordinates like the Amazoness Quartet for failures and demands absolute obedience in the mission to locate Pegasus and seize the Golden Crystal, thereby freeing Nehelenia from her mirror prison. Her magical abilities encompass projecting blue energy waves, generating spider-like threads, and creating duplicates to confound foes. She employs nightmare-inducing fog and dark barriers to ensnare cities, draining energy from captured civilians to empower Nehelenia. Overseeing the Dead Moon Circus, she commands the Amazoness Quartet and transforms a tiger, a hawk, and a fish into the humanoid Amazon Trio—Tiger's Eye, Hawk's Eye, and Fish Eye—tasking them with infiltrating dreams to find Pegasus. When the Trio fail, she dispatches the Quartet to eliminate them. During the Dead Moon Circus's invasion of Earth, Zirconia directs efforts to capture Sailor Guardians by exploiting their nightmares. She orchestrates energy-draining performances, covers the sun with a black moon to plunge Earth into darkness, and confronts the Sailor Guardians directly. After the Amazoness Quartet question their allegiance, she imprisons them along with Sailors Chibi Moon and Saturn within glass shards, delivering them to Nehelenia. She later traps the remaining Sailor Guardians and Tuxedo Mask in nightmares, though they eventually break free and wound her with a combined attack. Zirconia meets different ends across adaptations. In the original anime, Sailor Mercury identifies and attacks the real Zirconia amidst her duplicates, forcing her retreat. She vanishes when Nehelenia emerges from her mirror, unable to exist independently while Nehelenia is free. In *Sailor Moon Eternal*, she remains within Nehelenia's disintegrating mirror after Sailor Moon shatters it, declaring Nehelenia's eternal reign before both are obliterated by Eternal Sailor Moon's final attack.