To search for her missing younger brother who enrolled in Japan's prestigious all-boarding school, Teiou Academy, Shirakawa Rui infiltrates the campus as a teacher. Donning a White Mask, she resolves to defeat the masked faculty members who dominate students with overwhelming power. However, she is overpowered by a formidable teacher wearing an iron mask and ultimately defeated. The school principal, Ashura, unmasks her intentions and subjects her to humiliating interrogation, restraining her completely. As she begins losing consciousness from toxic gas, a potent stimulant is smeared across her breasts and sensitive groin, heightening her nerve sensitivity. Overwhelmed by sensation, she is driven to pleasure by a vibrator, only to have Ashura forcefully ejaculate deep inside her vagina. Still determined to protect her brother and keep her identity hidden, she suffers further torment as poison drips into her body through her nipples like an IV, while a hose injects more toxin directly into her crotch. The poison oozes from her pelvic area, and even as the iron-masked teacher prepares to penetrate her again, her mask remains intact—ushering her into an inescapable climax.