Parasyte -the maxim-

Alien parasites descend from the skies with a single requirement for survival: they must invade and take control of human hosts. Once established inside a victim, they can reshape themselves into deadly forms while hiding behind an ordinary human appearance. Most people have no idea these creatures are living among them. Shinichi Izumi, an otherwise ordinary high school student, becomes one of the few people directly caught in their arrival. Instead of simply disappearing into the growing population of infected humans, he finds himself fighting an alien parasite for control of his own body while confronting the wider danger the creatures pose to humanity.