Jibril

Jibril is the youngest member of the Flügel — an ancient, near-immortal race of winged mages — and one of its most powerful individuals despite that. Her love of knowledge predates even the treaty that ended the Great War: when the Flügel's ruling council passed a law forcing members to share their private libraries, she abandoned her homeland rather than comply, and instead won an entire kingdom's library from Elkia's previous king in a game.

That victory drew the attention of Sora, who challenged her for access to the same books; Jibril lost the match and, having bet her own existence on it, became his and Shiro's servant on the spot. Unlike Elkia's princess Stephanie Dola, who resents her own binding pledge, Jibril embraces servitude to the siblings without complaint, addressing them as Master and slowly discovering feelings for Sora she insists a being of her kind was never supposed to have.

Millennia of near-invulnerability, instant recall and combat experience make her one of the most dangerous individuals in Disboard: her signature spell, Heavenly Smite, once leveled an entire elven capital and cost her five years without magic as the price. She can be condescending toward races she considers beneath her, including the elf mage Fiel Nirvalen, but her honesty and hatred of cheating run just as deep as her arrogance.