Parasyte

A parasitic alien tries to take over high schooler Shinichi Izumi's body in his sleep, only to end up lodged in his right hand instead of his brain. Shinichi and the parasite — who names itself Migi — form an uneasy symbiosis to survive, as other parasites quietly replace people throughout the city, and Shinichi's own humanity is slowly reshaped by what he now carries inside him. A landmark seinen horror series about identity, predation, and what separates humans from the things pretending to be human.