Ulbireo Ladnarash is a 20-year-old male, born on January 30, standing 184 centimeters tall and weighing 62 kilograms. He has red hair and multicolored eyes—one green and one blue—resulting from iris heterochromia. His blood type is O.

As a member of the Goulart Knights, Ulbireo often serves as one of the group's older and more experienced figures. He demonstrates high combat capability and is renowned as one of the team's strongest fighters. His preferred weapon is a vividly red scythe that grows from his back. He is also able to wield the sword of his fellow knight, Nil, which becomes sheathed in a fiery aura when in his grasp.

Ulbireo radiates extreme self-confidence, narcissism, and arrogance. He believes himself completely irresistible to everyone and operates under the conviction that all people should obey him unconditionally. He routinely refers to his fellow knights as his personal servants and relishes placing himself in the spotlight to command attention. He is fond of declaring that rules are meant to be broken.

Despite his selfish and often irresponsible demeanor, he exhibits a sense of duty in combat, willingly acting unselfishly to protect others. He frequently seeks mission approvals from the unit’s commander, Chris Chiron, with whom he shares a close relationship that shows no apparent deference to rank.

He developed a particular dynamic with Nil, subjecting him to significant suffering by treating him more as a pet and servant than anyone else. Ulbireo takes visible pleasure in being responsible for the knights' actions. His overall role involves assuming considerable responsibility, both in battle and other affairs, for the smaller group of knights that includes Nil and Hokuto Aoi.