Yurika Ichinomiya rules as Student Council President at Saint Rei Seine, an elite institution where she enforces authoritarian control over students and faculty, demanding absolute obedience. Her leadership philosophy insists on refinement and noble behavior as essential student virtues, positioning herself as inherently superior and beyond conventional judgment. Publicly, she embodies regal authority, presenting as the undisputed queen of the school. This cultivated image masks her private activities: maintaining enslaved individuals called "Culy" whom she subjects to sexual humiliation, degradation, and a fusion of sadomasochism and psychological manipulation. These methods function as brainwashing to ensure total control over her victims.

Her background reflects an elite context fitting the institution’s emphasis on status, though specific family lineage or formative experiences remain undocumented. No narrative depicts evolution, redemption, or change in her motivations; she persists as a consistent manifestation of unchanging authoritarian control and concealed deviance. Within the visual novel’s narrative, she operates as a main character in an erotic sorority where new members endure debauchery as induction. Her role leverages dominance and enforces submission through extreme measures.