Parasyte: Part 2

Humanity is under attack by human-mimicking flesh-eating alien parasites. One parasite bonds with his young high school student host, and he convinces the parasite to help him stop the others.
Alien pods come to Earth and, naturally, start taking over Human Hosts. One such pod only manages to take over one human's, Shin Izumi, right arm. Together they grow and co-exist, all the while the other aliens are making meals of other humans; Shin feels he must put a stop to it all, but his alien, Migi, doesn't see why.