Kiseijuu: Sei no Kakuritsu (Parasyte -the maxim-)
Unbeknownst to mankind the world is quietly being invaded. Alien beings known as “Parasytes” begin infiltrating humans one by one, burrowing into their brains to take complete control of both their bodies and their identities. With an insatiable hunger for human flesh these cold and calculating creatures mutate into grotesque monsters who feed on the unsuspecting when they're not hiding behind the faces of everyday people. Only Shinichi Izumi, a lone high school boy, is aware of the terror lurking in plain sight. After one Parasyte's attempt to take over his brain ends in failure, Shinichi's right arm is instead possessed by this monster with a mind and an agenda all its own. As Shinichi and his unwanted cohabitant, “Migi,” struggle for dominance of his body, the alien infection continues to grow and so does the trail of bodies in its wake. Now Shinichi and Migi must become more than host and parasite if they hope to not only protect themselves, but Shinichi's loved ones as well. As Shinichi and Migi's symbiotic bond deepens, will Shinichi be able to hold on to his humanity, or will he evolve into something more than he ever imagined?
[Source: Sentai Filmworks]