Parasyte -the maxim-

Shinichi Izumi is a standard highschool boy whose proper hand has change into contaminated with an alien parasite that names itself “Migi” (“right”). Migi is the primary parasite to develop a symbiotic relationship with its host, as he and Shinichi slowly develop a grudging friendship. Migi is not the one Parasite on earth, nevertheless, and as instances of Parasites killing people start to emerge, people search to kill off Parasites. Shinichi and Migi discover themselves caught in between these two sides of the wrestle over planet earth.