Klara Kisenaria is a sensible and serious agent of the First Unit in the government agency Dorothea, which handles illegal fairy usage. She has long brown hair, bright blue eyes, and wears black-rimmed glasses, typically dressed in the standard Dorothea uniform.

Her motivations are shaped by a past experience during the war, where she was saved from soldiers by Nein Auler. This event led her to voluntarily receive a fairy organ transplant and join Dorothea out of loyalty. Klara operates primarily with Serge Tovah, though his laid-back and flirtatious attitude frequently annoys her. A capable fighter, she is proficient in both marksmanship and swordplay and often provides long-range support and reconnaissance.

Her fairy, Tomereez, is a small, frog-like creature too weak for direct combat but excels in infiltration and surveillance. By linking its senses with Klara, the fairy makes her highly effective for reconnaissance and acting as a spotter for Serge Tovah's sniping.

Key operations include monitoring events at Derpe's ruin with her fairy, providing support during encounters, and teaming with Marlya Noel to investigate a Black Fairy Tome page. On that mission, they confronted an informant and captured a target on a train. She also assisted in an operation at Gilbert Warlock's estate, using Tomereez to signal other agents and confuse attackers. Klara participated in a mission to guard Ray Dawn, which involved a sabotaged train and an attack at a ruined castle where artificial fairy soldiers were deployed, consistently demonstrating her role as a supportive and effective agent.