Wilibald Koenig operates as a frontline aerial mage in the 203rd Aerial Mage Battalion under the command of Tanya von Degurechaff. Possessing a tall stature and sharp facial features, he wears his long, dark brown hair secured in a low ponytail, with narrow eyes that reflect his focused demeanor. His duties encompass direct combat roles, reconnaissance operations, and coordinated strikes against adversaries such as the Russy Federation and Allied Kingdom forces.

During the pivotal defense of Tiegenhoff, a critical railway hub, Koenig aided the 203rd in countering relentless human wave assaults and enemy aerial incursions, showcasing his strict adherence to tactical discipline and seamless coordination with unit members under duress. Beyond combat, he engages in casual camaraderie with fellow soldiers during downtime, including participation in celebratory events.

In crossover narratives, Koenig interacts pragmatically with external characters, such as firmly correcting Aqua’s use of informal nicknames. He adapts to collaborative scenarios like team sports, including baseball and dodgeball, maintaining a cooperative yet disciplined approach aligned with his military background.