Martes is a humanoid slime entity whose form consists of multiple interconnected slime-based lifeforms. Her gelatinous physiology enables physical manipulation and division into smaller autonomous units. She serves as a core member of the Extractors team, specializing in infiltration and combat operations that exploit her malleable nature.

Deep devotion to Equa defines Martes, manifesting as fierce protectiveness and admiration. This loyalty drives her actions, especially during high-stakes missions. Her combat capabilities feature rapid division into smaller slime entities to overwhelm opponents and the absorption of impacts fatal to organic beings. During the Oedo Castle infiltration, she fragmented into numerous miniature versions to disable security drones, temporarily sacrificing physical cohesion to protect the team. Later, she wielded a specialized hammer in close-quarters engagements.

Martes develops through interpersonal conflicts, notably when mediating disagreements between Equa and Feles. She champions team unity and demonstrates increased assertiveness in critical moments. Following the extraction of the ecosystem AI, Martes resumes operations at Cafe Vostok while continuing extraction missions. Her capacity for forming emotional bonds remains central to her interactions, particularly with Equa.