Parasyte

寄生獣

High schooler Shinichi Izumi wakes one night as a worm-like alien tries to burrow into his brain through his ear. He blocks it, and the creature instead takes over his right hand, becoming a separate intelligence he names Migi. Other parasites have already replaced human hosts entirely and hunt people for food, leaving Shinichi and Migi an uneasy pair who must cover for each other to survive. As Migi learns about humanity and Shinichi confronts what is now living in his body, the two work out how to coexist while staying hidden from their own kind.