Quartz Christie commands the experimental battleship Grand Cross as an imperial pirate sanctioned by the Galactic Empire. She belongs to the imperial royal family, being the daughter of Queen Utolamela Christie. Following imperial tradition, her Grand Tour across space led her to become an imperial pioneer and pirate. This path resulted in her captaincy of the next-generation prototype vessel Grand Cross; she began training shortly before the reported death of Gonzaemon Kato. Quartz utilized the ship to conduct field tests by attacking frontier pirates, driven by her conviction that they had forsaken true piracy and were merely relics of a bygone era.

Physically, Quartz possesses pale skin, striking silver-white hair, and distinctive golden eyes. Her appearance features light blue lipstick and dark blue eyeshadow. Her hair exhibits a light blue glow during direct interfaces with the Grand Cross's technology. She typically wears a form-fitting white and grey bodysuit with black gloves, its surface often shimmering with sparkling squares—an effect associated with portable stealth camouflage. For significant confrontations, such as her address to assembled pirate captains at the Pirate's Nest, she dons a black cloak bearing a gold skull insignia signifying her status as an imperial pirate captain.

Her personality displays pronounced pride, overconfidence, and arrogance. She strongly dislikes being upstaged and holds particular contempt for frontier pirates, viewing them as cowardly and inauthentic for relying on Letters of Marque to stage entertainment-focused raids instead of what she deems genuine piracy. This disdain fuels her willingness to destroy pirate ships during her "testing" operations, treating them as expendable tools to validate the Grand Cross's capabilities. Imperial associate Ironbeard, tasked with overseeing her, refers to her as a tomboy, reflecting her headstrong nature.

Quartz's primary narrative arc centers on her campaign hunting frontier pirate vessels. After initial successes, she engaged the Bentenmaru, captained by Marika Kato, but retreated due to intervention by Ironbeard's ship, the Parabellum. Undeterred, she later ambushed the Bentenmaru en route to the Pirate's Nest using intelligence from an android spy, though Marika's crew escaped despite significant damage. Quartz infiltrated the Pirate's Nest, confronting Marika directly. She revealed her identity as the Grand Cross captain, criticized the frontier pirates' perceived inauthenticity, and declared them unnecessary before vanishing via stealth technology after Marika vowed resistance.

Her subsequent appearance at the Pirate's Nest assembly provoked hostility. Marika intervened, invoked the sanctuary's no-killing rule, and issued a formal challenge for a fair fight. Quartz accepted with a confident smirk, though dramatic stagelights accompanying the challenge visibly irritated her. Ironbeard arrived under orders from the Empress to retrieve her. During their exit, Quartz expressed frustration that both Marika and Ironbeard had stolen her intended dramatic impact. An assassination attempt by renegade pirates further solidified her low opinion of frontier pirates as cowards. She later mocked Marika and Chiaki's broadcasted pirate song with her own rendition.

The decisive battle occurred at the location specified by the pirates' broadcast. Quartz arrived commanding three Grand Cross vessels, initiating immediate electronic warfare. Though impressed by the pirates' linked network countering her attack, she remained confident. Her tactics relied heavily on the Grand Cross's technological superiority and a repetitive zigzag attack pattern. This predictability proved fatal. United pirate forces, anticipating her maneuvers, used sacrificial chaff fields and coordinated fire to disable Grand Cross β and γ. Enraged, Quartz focused Grand Cross α on the Bentenmaru. However, the Shangri-La rammed her ship, enabling a boarding party led by Marika to reach the bridge. Quartz awaited Marika there, commented on her flashy outfit, and engaged in a final debate about piracy's nature. After Marika countered her arguments, Quartz escaped via the ceiling as Schnitzer moved to capture her, warning of the ship's imminent self-destruction. Fleeing in a Silent Whisper escape pod, she acknowledged collecting experimental data and destroying evidence, conceding her pride was demolished. She expressed a belief in meeting Marika again.

Beyond the anime, Quartz Christie and the Grand Cross feature in the game Fever Mouretsu Pirates. Within its eighth Galaxy Episode, she opposes Marika and the Bentenmaru. Player actions determine whether their confrontation occurs as a direct swordfight or a ship-to-ship battle, dictating the outcome. The conflict against the Grand Cross also appears as a standard pirate mission within the game.

Her technological arsenal includes the Grand Cross battleship, android spies, and portable stealth camouflage. However, her reliance on technological supremacy becomes a weakness; she tends to deploy the same tactics regardless of the situation and fails to utilize her equipment to its full potential, prioritizing overwhelming force over adaptability. This inflexibility significantly contributes to her defeat.

Regarding relationships, Marika Kato first garnered Quartz's attention as the first captain to escape the Grand Cross. While initially dismissive like other frontier pirates, Quartz developed a degree of respect following their confrontation and Marika's role in her defeat. Her interactions with Ironbeard are marked by annoyance, particularly when he thwarted her initial attack on the Bentenmaru and intervened at the Pirate's Nest, though he operates under the Queen's authority. Her mother, Utolamela Christie, cares for her but questions her upbringing given Quartz's attitude. Frontier pirate captains uniformly hold animosity towards her due to her attacks.

A notable operational detail is her exclusive use of machine-based crew aboard the Grand Cross, contrasting with typical pirate crews.