Osmond, known as Old Osmond, presides over Tristain Academy of Magic as its headmaster. A venerable Square Mage of wind affinity, he commands formidable authority and arcane expertise, offering shrewd counsel during pivotal conflicts. His demeanor marries sagacity with a roguish streak: he deploys his mouse familiar, Motsognir, to covertly observe his secretary Longuevuille’s lingerie or feigns senility to obscure his schemes.

Three decades before the central timeline, a dragon attack stranded Osmond until rescue arrived via an American Vietnam War soldier wielding a rocket launcher. The soldier perished moments later, prompting Osmond to bury him with one launcher while gifting the second to Tristain’s royalty as the revered "Staff of Destruction"—an encounter that cemented his grasp on cross-dimensional phenomena and informed his stewardship of otherworldly relics.

At Louise’s Familiar Summoning Exam, he witnesses her conjuring Saito Hiraga, later confiding with Professor Colbert about the boy’s Gandálfr runes and their ties to the Void—a primordial magic entwined with Louise’s bloodline. Osmond mandates secrecy around this revelation, wary of its political ramifications. When Fouquet pilfers the Staff, he dispatches Louise, Kirche, and Tabitha to reclaim it, unknowingly assigning Longuevuille—Fouquet’s alter ego—to chaperone their mission. Post-recovery, he discloses the weapon’s origins to Saito, threading it back to the fallen soldier.

An OVA sideline sees Osmond mastermind a ruse involving swimsuits from Saito’s world, rebranded as sacred attire to coax female students into donning them for a fictitious water spirit rite—showcasing his penchant for weaving mischief into duty.

Balancing eccentricity with governance, Osmond safeguards the academy’s integrity amid external threats and volatile artifacts. His methods, sometimes ethically nebulous, remain unwaveringly devoted to shielding both institution and pupils from harm.