Framed for a crime he did not commit, Kyousuke Kamiya is sent to Purgatorium Rehabilitation Academy. Suddenly, he finds himself surrounded by a variety of attractive girls—each one a murderer! To make matters worse, he is infamous as the "Dozen Demon," a killer blamed for twelve deaths! When Renko Hikawa, a busty beauty wearing a gas mask, approaches him, the line between death and desire becomes razor-thin. How is Kyousuke going to graduate alive?