Kōmori, alias Bat, is a recurring antagonist for the secret organization SPES. He possesses short blond hair, green eyes, and typically wears a dark gray suit, gray pants, and black dress shoes. An artificial human, his engineered biology grants enhancements including a scorpion tail-like appendage extending from his left ear when activating his android capabilities. Reportedly Scandinavian and 34 years old, he lacks natural eyesight, compensated by enhanced auditory abilities.

His personality is deceitful and cowardly, often driven by whimsical self-interest rather than loyalty to SPES. Early in the series, he hijacked an international flight; this event inadvertently led to the first meeting between detective Siesta and her future assistant Kimihiko Kimizuka and concluded with his defeat by them.

Kōmori's backstory reveals his real name is Albert, disclosed in later light novel volumes. He had a sister who died during unethical SPES experiments, an event that profoundly impacted his past and motivations, connecting him to the organization's history of human experimentation.

His engineered physiology provides his primary abilities, including heightened senses and physical transformations reflecting his bat-inspired codename. As a SPES operative, he participates in their efforts to sow chaos, though his personal unpredictability sometimes undermines their objectives.