Klara Kisenaria, a serious and sensible member of Dorothea's First Unit, regulates illegal fairy usage. She possesses long brown hair, blue eyes, and wears black-rimmed glasses with the standard Dorothea uniform, often contrasting with her more carefree colleagues. A formative wartime trauma, an attempted assault by three soldiers halted only by Nein Auler's rescue, cemented her loyalty to him. This drove her to voluntarily undergo a fairy organ transplant and join Dorothea.

Her fairy, Tomereez, resembles a small frog and lacks direct combat power. Instead, its diminutive size and ability to evade detection enable sensory linkage, making Klara highly effective for infiltration, surveillance, and reconnaissance. She frequently acts as a spotter for Serge Tovah's sniping missions. Klara herself demonstrates proficiency in both marksmanship and swordplay.

Her critical missions include monitoring Derpe's ruin and providing overwatch; accompanying Marlya Noel to interrogate an informant about the Black Fairy Tome aboard a train, where they subdued attackers and captured a target; assisting Bitter Sweet against Gilbert Warlock, using Tomereez to signal Dorothea reinforcements while disorienting hostiles; guarding Duke Ray Dawn alongside Free, Marlya, and Serge, defending their group overnight in a sabotaged train and ruined castle against artificial fairy soldiers; and caring for the injured Lily Heineman during an attack, freeing Marlya to pursue an enemy.

While Klara coordinates effectively with Serge Tovah in the field, she displays visible annoyance at his flirtatious behavior. Her commitment to Dorothea's objectives remains unwavering, fueled by deep-seated gratitude toward Nein Auler and dedication to maintaining postwar stability.