George L. Gregory is a police inspector heading a specialized Scotland Yard department dedicated to supernatural incidents involving entities called Umbras or Shadows. His duty is to investigate and resolve cases related to these non-human entities while ensuring their existence remains hidden from the public. This department works to maintain the boundary between the human world and the shadow realm.

Gregory maintains a professional working relationship with the guardians of Café Forbidden, a midnight establishment serving as a gathering point for those protecting the boundary between humans and shadows. He collaborates with its members on investigations into supernatural incidents, such as assisting in locating a kidnapped individual early in the series. His role involves coordinating between law enforcement and the Café Forbidden team to address threats from the shadow world.

His operational approach prioritizes discretion and containment, focusing on preventing public awareness of supernatural phenomena. Gregory appears during critical incidents requiring coordination between human authorities and shadow guardians, like the investigation into the disappearance of Ton's friend Shinyao Mu. His involvement typically supports the efforts of the Café Forbidden team rather than taking direct action against supernatural threats himself.

Information regarding Gregory's personal background, character development beyond his duties, or appearances in additional media remains unavailable. His documented role is confined to his function within Scotland Yard's specialized department and his cooperative efforts with Café Forbidden during specific cases.