Known as the ruthless squad leader of the Kodama unit, Rumi is regarded as the most powerful presence within the investigation bureau. However, after constantly pushing herself in the male-dominated world of security personnel, she maintains a tough, dominant front with her big tits and commanding attitude, while secretly harboring an intense inner desire as a true masochist. Targeting this hidden vulnerability is a mysterious psychological counselor. Under the guise of a psychological evaluation, she initiates a series of BDSM sessions, gradually penetrating Rumi's defenses and uncovering her deepest, most submissive nature.