Kiseijû

High school student Izumi Shinichi has a parasite living off him, having replaced his right hand, and he might be the discoverer of truth. He befriends the parasite and names him "Migi", which leads to a symbiotic relationship as Migi tries to join its kind. The parasites terrorize humanity by secretly killing them as sources of food, and Shinichi must fend against them. Meanwhile, a high school teacher, Ryoko Tamiya, becomes infected with a parasite, and her pregnancy with the creature's offspring poses a unique challenge to the situation.