Based on the erotic game by Speed. Oogami Island is normally a peaceful isle with lush green scenery, but is now a place of depraved wanton lust. The contagion Unknown - Level 4 has become epidemic. 3 girls, Hyuuga Natsu, Ochi Akari, and Hanazawa Airi find themselves trapped in a sports facility where they are assaulted by the infected.