Aldra, a half-demon born to the Pope and the Devil King’s daughter, endured persecution alongside her sister until their separation during a desperate search for food. Driven by loss, she forged a pact with the demon Delmore, gaining immense power—a petrifying gaze and hidden blades—in exchange for an eternal bond that froze her physical growth, trapping her in a childlike form. Ascending as Queen of Gainos through back-to-back Queen’s Blade victories, she ruled with icy detachment, channeling her authority into a relentless hunt for her missing sister. Court sorcerers, fearing her wrath, fed her fabricated letters to sustain her hope, ensuring her grip on power through further conquests. Her reign was marked by military crackdowns, covert assassins, and an arena littered with stony monuments to her petrified foes.

Defeated by Leina in a later tournament, Aldra lost Delmore, triggering a metamorphosis into her true adult physique and erasing her memories. Adrift, she encountered a man who became her husband, adopting a buoyant, protective persona. To shield him, she bound herself to new Netherworld entities, Belphe and Dogor, unaware of their hidden intent to devour her.

Her "Unlimited" incarnation later unveiled wings, a tail, and a crown, with Delmore reborn as a female companion. Her arsenal shifted to a serrated curved blade, her eyes shifting from crimson to emerald, reflecting unleashed demonic power. This evolution amplified her summoning prowess and aerial combat mastery, underscoring her unbridled heritage.

Aldra’s relationships shaped her fate: her fraught bond with Delmore, warped by his unreciprocated devotion; a marriage symbolizing rebirth, hinted to transcend conventional narrative boundaries; and her unresolved quest for her sister, Annelotte Kreutz—a ghost of tragedy propelling her ceaseless resolve.