Discipline Zero delves into the depraved origins of St. Alcadia Academy's reign of sexual terror, chronicling the rise of the ruthless dominatrix Leona Morimoto. Upon her arrival, Leona immediately establishes a brutal hierarchy, using blackmail, psychological torture, and overwhelming physical force to break the wills of students and faculty alike. Her primary target, the initially defiant Saori Otokawa, is systematically humiliated and sexually degraded through a series of perverse trials. The series graphically depicts Leona turning the academy into her personal harem of pleasure slaves; girls like Saori, Maiko, and Ruri are forced into hardcore group sex, gangbangs, and lesbian encounters, their bodies used as public fuck-toys. Male students and even teachers are subjected to feminization and forced to service the female students, often with strap-ons. Leona's cruelty knows no bounds, featuring scenes of anal and oral violation, double penetration, and extreme BDSM play, all orchestrated to shatter her victims' minds and remold them into obedient, cum-addicted pets whose only purpose is her sexual gratification.