They arrive in silence and darkness. They descend from the skies. They have a hunger for human flesh. They are everywhere. They are parasites, alien creatures who must invade - and take control of - a human host to survive. And once they have infected their victims, they can assume any deadly form they choose: monsters with giant teeth, winged demons, creatures with blades for hands. But most have chosen to conceal their lethal purpose behind ordinary human faces. So no one knows their secret - except an ordinary high school student. Shinji is battling for control of his own body against an alien parasite, but can he find a way to warn humanity of the horrors to come?