寄生獣

High schooler Shinichi Izumi wakes one night to find a worm-like alien burrowing toward his brain. He ties off his arm in time, and the creature settles in his right hand instead, 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 faces what now lives in his body, the two work out how to coexist while staying hidden.