Rei Izumi, a 26-year-old law enforcement officer born March 13, serves in the Ministry of Health, Labour and Welfare's narcotics investigation unit. Standing 160 cm tall, she possesses shoulder-length brown hair swept to the left and distinctive violet-purple eyes. Her background as a pharmacist led to recruitment after authorities identified her rare DNA, granting complete immunity to drug effects—especially potent and hazardous substances. This unique physiology makes her a target for criminal organizations aiming to exploit her for drug testing.

Initially joining as a probationary officer following an accidental facility check incident, Rei secured a permanent role focused on recruiting members for STAND, a specialized agency combating narcotics. Her recruitment targets span multiple factions: Matori, Revel, The Kujou Family, and the Tsuzuki Brothers. Professionally, she evolved from early impracticalities like high heels and disheveled hair, adopting flats and a shorter haircut for operational efficiency.

Driven by a strong moral compass, Rei demonstrates a determined personality and acts decisively when justice is compromised. While primarily dedicated to investigative duties, she occasionally displays admiration for attractive colleagues without sacrificing professionalism. Her later investigative work, depicted in the OVA "Warmth of Memories," further explores her role within STAND's operations.