Parasyte

All of a sudden, parasitic aliens descend upon Earth and begin infiltrating humanity by burrowing into the brains of vulnerable targets. These insidious beings acquire full control of their host and are able to morph into a variety of forms in order to feed on unsuspecting prey. Sixteen-year-old high school student Shinichi Izumi becomes infected by one of these parasites, but it fails to take over his brain and ends up in his right hand. Unable to relocate, the parasite, now named Migi, is forced to rely on Shinichi in order to stay alive. Thus, the pair is forced into an uneasy coexistence, and must defend themselves from hostile parasites that hope to eradicate this new threat to their species.