Kyoka Tsujigai supervises Sanctuary, a special rehabilitation ward for latent criminals under the Ministry of Economy, Trade and Industry's Environment Bureau. This facility differs from standard isolation by emphasizing therapy and communal integration, where inmates mine rare metals for surveillance drones. She possesses average height and a slender build, with features suggesting her 40s, light brown eyes, and mid-length gray hair styled in a flip. Her typical attire includes a cinched white jacket with gray piping, a red blouse, black pants, earrings, and often a yellow ruana shawl. Outwardly articulate and pleasant, Tsujigai holds a dehumanizing view of latent criminals, considering them expendable assets for societal benefit. She oversees an experimental program combining hypnotherapy and a specialized drug, developed with scientist Ataru Takeda, inducing a state of group think among inmates. This ensures absolute compliance, allowing her to assign hazardous tasks like handling radioactive materials without protective gear, all rationalized as serving the "greater good." Her crime coefficient of 421, revealed during an inspection, underscores her own psychological deterioration. Credentialed as both a scientist and therapist, Tsujigai operates with the approval of government official Akira Karasuma. She actively promotes her methods as the optimal rehabilitation model while concealing their exploitative nature. Her background involves monitoring Sanctuary's staff and inmates, perpetuating the facility's guise of a "paradise." Her relationship with Rodion Matsuki, Sanctuary's chief security officer and a latent criminal, appears collaborative, rooted in shared disdain for inmates. Matsuki later expresses remorse after failing to convert Inspector Nobuchika Ginoza to his beliefs, culminating in his suicide. Within the narrative, Tsujigai orchestrates the central conflict of Sinners of the System Case 1. Her manipulation of therapist Izumi Yasaka—who consumed drugs intended for patient Takeya Kukuri to protect him—triggers Yasaka's escape to Tokyo and the subsequent Public Safety Bureau investigation. This inquiry exposes Tsujigai's coercion of Yasaka, unethical drug use, and the facility's exploitation of inmates for dangerous labor. Her downfall occurs when Inspector Mika Shimotsuki and Enforcers uncover these abuses, designating Tsujigai as an enforcement target. The etymology of her name reflects her role: "Kyoka" combines "barbarian" (羌) and "fragrance" (香), while "Tsujigai" merges "street/crossroad" (辻) and "domesticate/raise" (飼). Born in 2066, she is 51 years old during the events of February 2117.