The series follows Kiriko Ragawa, a beautiful and physically capable math teacher with black belts in karate and judo. A group of her male students, who have a history of preying on female teachers, decide to make her their next target. They successfully capture and bind her in the school building, intending to break her strong will through sexual degradation. The first episode establishes their sadistic game: they challenge Kiriko that if she can endure ten minutes of them playing with her body without getting wet, they will release her. Initially, her powerful spirit and body resist their perverse assaults, but she is eventually overwhelmed by forced pleasure. Over the course of the series, she is subjected to escalating acts of humiliation and violation, including repeated gangbangs. Her students relentlessly assault all of her orifices, forcing her to fellate them and taking her vaginally and anally until her mind and body are completely shattered. The arc details her tragic transformation from a proud, strong woman into a broken, sexually depraved slave who eventually succumbs entirely to the carnal debauchery forced upon her, fulfilling the series title of 'Depravity'.