Kansen

A mysterious plague is spreading through the school, making students and teachers alike uncontrollably turned on. Kazumi rescues his stepsister Tsugumi from a group of the sex-crazed infected, and together they take refuge with Tsugumi's friend Shizuka and the few remaining survivors. But in the shower room, Tsugumi begins to reveal her slutty past to Kazumi, as Shizuka secretly watches. Is Tsugumi infected? Can Kazumi resist his horny stepsister's advances?