Reika Kobato operates as a Sleeper within Antarctica Front Platoon Unit 11, conducting perilous missions in the hazardous subterranean Asylum. She has shoulder-length gray hair, blue eyes, and wears glasses, a choker, and gloves during operations. A prosthetic right leg, concealed beneath her attire due to self-consciousness, resulted from an undisclosed past accident.

An accomplished artist with a passion for manga, anime, and otaku culture, these interests subtly color her interactions and worldview. Her personality blends compassion and a strong drive for justice, often compelling her to aid others despite personal risk—a tendency that can cause friction with more pragmatic teammates. While reserved around strangers, she demonstrates analytical skill, independence, and decisiveness in the field.

Functioning as the platoon's firearms combat specialist, she collaborates directly with commander Vera Rustamova and executive officer Leslie Blanc. Her duties involve confronting hostile "Scarred" entities and navigating complex organizational conflicts surrounding EL-Cee, the "Child of God." Facing ethical challenges and the consequences of tactical decisions within the Asylum has honed her adaptation to its psychological and physical demands. These experiences foster her gradual self-acceptance regarding the prosthetic limb and reinforce her commitment to protecting her team.