The Circle is the core antagonist force in YiHuan's main story. This mysterious organization has mostly unidentified members, but they are known to possess anomalous technology far exceeding that of the Bureau of Anomaly Control — the ability to actively create and control anomalies. The Circle's members all appear to possess unique esper abilities and operate outside the Bureau's jurisdiction.
The Circle's name comes from its symbol — a circular ring with no beginning or end. This symbol appears at multiple anomaly sites and serves as a key clue for the Appraiser to identify Circle activities. The organization's internal structure follows a strict hierarchy, with high-ranking members called 'Guardians,' each responsible for anomaly operations in different areas.
The Circle's ultimate goal is related to ancient oaths and prophecies. They believe the current esper order is wrong and seek to trigger the 'Great Transformation' described in prophecies through large-scale anomaly events — an event that would fundamentally alter the nature of the world. The confrontation between The Circle, the Eibon Antique Shop, and the Bureau of Anomaly Control forms the main conflict of the story.