Izumi Yasaka is a 27-year-old licensed psychological counselor employed by the Ministry of Welfare, assigned to Sanctuary, a latent criminal isolation and rehabilitation facility in Aomori Prefecture. Standing 1.63 meters tall and weighing 48 kilograms, with brown hair, brown eyes, and blood type A, she is authorized under Ministry regulations and participates in the facility's therapeutic programs. Her background includes counseling Momoka Kukuri, a Sanctuary patient who died under suspicious circumstances. Following Momoka's death, Izumi fled the facility with Momoka's young son, Takeya Kukuri, aiming to protect him from Sanctuary's operations. She hid Takeya in a cemetery mausoleum before traveling to Tokyo seeking help from the Public Safety Bureau. Her vehicle crash at the Bureau initiated the investigation into Sanctuary. During her escape and subsequent apprehension, Izumi exhibited severe psychological impairment, manifesting as incoherent speech and fragmented communication. This resulted from her sacrificially ingesting experimental drugs intended for Takeya. These drugs enforced compliance through "Collective Thinking," a drug-altered group consciousness suppressing individual dissent. Her act caused significant cognitive dysfunction, rendering her nearly unintelligible. Izumi's actions directly exposed Sanctuary's covert operations. She revealed the facility exploited latent criminals to excavate hazardous nuclear waste buried beneath the mine, causing fatal radiation exposure among inmates. She also uncovered the use of experimental treatments to enforce psychological conformity, framing dissent as a capital offense. Her testimony, preserved on Takeya's memory chip and later recovered, provided critical evidence of these crimes. Following Sanctuary's dismantling, Izumi entered rehabilitation to recover from the drug's effects. By the conclusion of events, her psychological state improved, regaining coherent speech and emotional stability. She maintained a protective relationship with Takeya and expressed intentions to secure his custody from state care upon her full recovery.