Ais Wallenstein stands as a first-class adventurer and executive member of the Loki Familia, celebrated throughout Orario as the "Sword Princess." She possesses long golden-blonde hair, striking gold eyes, and a slender physique. Her typical battle attire consists of white and black cloth beneath protective armor including a head guard, breastplate, arm guards, hip guards, and knee guards. Outside the Dungeon, she favors a white one-piece dress accented with gold lining. Characterized by quiet reserve and difficulty expressing emotions verbally, she often appears mysterious or aloof. Yet beneath this exterior lies a mental youthfulness, sometimes visualized as a younger version of herself during moments of vulnerability. An intense, revenge-driven goal defines her: to defeat the One-Eyed Black Dragon, responsible for her mother's disappearance in her childhood. This trauma fuels a deep-seated hatred of monsters, initially manifesting as irrational aggression and self-destructive behavior in her relentless pursuit of strength. As a child, volatile tendencies led her to disrespect authority and neglect her well-being in combat, earning her the moniker "Doll Princess." Joining the Loki Familia at age seven, she began as a supporter before rapidly ascending as an adventurer. She achieved Level 2 within a year—a record later surpassed by Bell Cranel—and continued leveling at an exceptional pace, reaching Level 4 within 1–1.5 years per rank. Her early obsession with physical prowess was tempered by mentorship from Loki Familia executives: Finn emphasized mental fortitude and technique, Riveria provided magical tutelage, and Gareth instilled the importance of rest. Despite this guidance, her vengeful drive persists, occasionally surfacing when activating her Avenger skill or confronting limitations. Her combat specialization is monster slaying. As a Level 6 adventurer, she wields exceptional strength, speed, and agility, capable of creating afterimages and shattering adamantite structures. Her primary weapon is Desperate, an unbreakable Durandal-attributed sword. She commands the wind enchantment magic Ariel for both offense and defense, alongside the skill Avenger—amplifying attack power against monsters, especially dragon-types, at the cost of weapon durability and mental clarity. Her development abilities include Hunter (bonuses against previously fought monsters), Abnormal Resistance, Swordsman, and Spirit Healing. A complex relationship unfolds with Bell Cranel. Initially intrigued by his rapid growth and rabbit-like appearance, she assists him multiple times: rescuing him from a Minotaur, offering a lap pillow during recovery, and providing secret training. Their interactions evoke previously unseen happiness in her, culminating in accepting his dance invitation at the Apollo Familia's ball—her first dance. Though romantic feelings develop, her revenge goal creates inner conflict, as she believes it precludes her from becoming a true hero. Her worldview shifts during the Xenos incident. Initially rejecting the notion that monsters could possess empathy, she reconsiders after witnessing the Xenos Wiene protect Bell. This experience destabilizes her resolve, leading to uncertainty about monsters' inherent evil. Following training with Ottar, she concludes that both monsters and humans can harbor emotional depth or monstrous hearts, resolving to personally judge whom to classify as monsters. Notable quirks include hydrophobia stemming from a childhood "swimming training" incident with Riveria, and a gullibility exploited by Loki—such as believing revealing outfits enhance combat effectiveness. She maintains close bonds with Riveria, who serves as a maternal figure, and Lefiya Viridis, though her past remains a closely guarded secret shared only with Loki and the top executives.