Parasyte

Parasyte centers on a 17-year-old male named Shinichi Izumi, who lives with his mother and father in a quiet neighborhood inTokyo. One night, worm-like creatures called Parasites appear on Earth, taking over the brains of human hosts by entering through their ears or noses. One Parasite attempts to crawl into Shinichi's ear while he sleeps, but fails as Shinichi is wearing headphones, and enters his body by burrowing into his arm instead.Because Shinichi was able to prevent Migi from travelling further up into his brain, both beings retain their separate intellect and personality.I love this anime it's so cool.