Maruteese, also known as Martes in some sources, is a 16-year-old slime girl who serves as a frontline combatant and crafting specialist for the Extractors, an illegal escape assistance group operating within walled city clusters. Her entire body is composed of slime, granting malleable properties used for tactical advantage. She maintains a surface identity as a high school junior within the Ochanomizu University City cluster, attending the same institution as fellow Extractors Ekua and Feresu.

Her personality is consistently bright, energetic, and lively. She displays significant affection toward team leader Ekua, frequently deferring decision-making to her, a core aspect of her group dynamics. Despite her combat role, she shows no overt aggression outside missions.

During Extractors operations, she specializes in close-quarters combat and technological fabrication, leveraging her slime physiology. Her responsibilities include crafting equipment and providing frontline support alongside teammates like the wolf beastman Ulula and robotic member Alga. Outside extractions, she helps maintain the team's cover at Cafe Vostok, though her specific duties there are unspecified.

Details regarding her appearance, involvement in supplementary media like "Bloody Escape: Jigoku no Tōsō Geki" or "Unity Memories," or substantive character evolution beyond her established series role are not referenced. Her background prior to joining the Extractors, including origins and recruitment, remains undocumented.