Originating as an Inverse Spirit from the Neighboring World, the White Queen's appearance closely mirrors Kurumi Tokisaki. She possesses long white hair in symmetrical twin tails, ivory skin, a red-tinted right eye, and a blue clock embedded in her left eye. Her attire consists of a white military-style dress with epaulettes, an admiral's cap displaying a rising sun emblem featuring a clock face, white gloves, and heeled boots.

Originally Sawa Yamauchi, Kurumi Tokisaki's human childhood friend, she transformed into a monster after receiving an incomplete Sephira crystal. Kurumi, failing to recognize her, accidentally killed Sawa. Sawa's soul merged in the Neighboring World with a discarded, inverted Kurumi clone created by the Eighth Bullet <Het>, replicating Kurumi's near-inversion state from that event. This fusion birthed the White Queen, driven by shared resentment toward Kurumi and their tragic world.

Proclaiming herself Dominion of the Third Region (Binah), she established a fascist regime, transforming it into a laboratory for torturing and experimenting on Quasi-Spirits and Kurumi clones. These experiments distorted victims into monstrous "Empty" or "Jabberwocky" soldiers for her army. She waged prolonged warfare to conquer other Regions, sacrificing subordinates indiscriminately. Her actions stemmed from anti-Quasi-Spirit ideology and a desire to annihilate the dimension she deemed an abomination.

Self-inflicted exposure to the Scorpio Bullet <Akrab> fractured her personality into six identities. Primary personas include:
- **Overlord**: The dormant core identity representing Sawa's original self, using polite speech masking profound malice and vengeance.
- **General**: A battle-focused persona dominant during campaigns, exhibiting smugness and strategic brutality.
- **Lady**: A regal, manipulative persona specializing in seduction and covert corruption, sharing Kurumi's love for Shido Itsuka. She aims to escape to the human world, rule alongside Shido as "king," and sacrifices the Neighboring World to achieve this.
Personality shifts occur mid-sentence, causing visible distress. Each identity employs distinct strategies—from overt invasions to psychological infiltration—to spread influence.

Her Demon King, Lucifugus, manifests as an astronomical clock, saber, and flintlock pistol, granting spatial manipulation powers distinct from Kurumi's time abilities. Key techniques include:
- **Cancer Sword Sartan**: Warps spacetime for offense or defense.
- **Leo Bullet Arie**: Fires a space-devouring projectile annihilating matter and leaving destructive trails.
- **Virgo Sword Betulah**: Opens spatial cracks for instantaneous inter-Regional travel.
- **Libra Bullet Moznaim**: Reverses cause and effect within a controlled area.
- **Scorpio Bullet Akrab**: Enslaves victims as chess-piece subordinates (Rook, Knight, Bishop), with Bishop capable of infecting others to create duplicates.
- **Gemini Bullet Teomim**: Generates expendable Empty soldiers.
- **Sagittarius Sword Keshet**: A single-use, Mach 10 projectile capable of gouging space, deployed solely in her final battle.

She masterminded death games in the Ninth Region (Yesod), luring Quasi-Spirits with false promises of wishes to harvest power from defeated participants. Infiltrating by disguising herself as Hibiki Higoromo, whose true form was transformed into a cat, she confronted Kurumi at the climax. Revealing her identity as Sawa, she expressed a desire for reconciliation. Kurumi rejected this due to her unforgivable actions, leading to a battle where the White Queen sustained mortal wounds. She perished after a brief moment of reconciliation with Kurumi, restoring Hibiki to her original form.