http://cdn.myanimelist.net/images/anime/3/65165.jpg
Plot:
The 17-year-old Izumi Shinichi lives with his mother and father in a quiet neighborhood in Tokyo. One night, worm-like aliens called Parasytes invade Earth, taking over the brains of human hosts by entering through their ears or noses. One Parasyte attempts to crawl into Shinichi's ear while he sleeps, but fails since he is wearing headphones, and enters his body by burrowing into his arm instead, taking over his right hand and is named Migi.
Because Shinichi was able to prevent Migi from traveling further up into his brain, both beings retain their separate intellect and personality. As the duo encounter other Parasytes, they capitalize on their strange situation and gradually form a strong bond, working together to survive. This gives them an edge in battling other Parasytes, who frequently attack the pair upon realization that Shinichi's human brain is still intact. Shinichi feels compelled to fight other Parasytes, who devour humans as food, while enlisting Migi's help.
I hate discussing anime in the general thread so here's one for this.
I really enjoy the dynamic between the MC and Migi so far. There's a lot of potential for that relationship to evolve. No other characters have really stood out so far but I'm interested to see what villains will pop up. The suspense surrounding the parasyte invasion is gonna be interesting to follow as well.