Hero?

A anime turn into a movie. 
Parasyte Part I

A Japanese teen manages to stop an alien infection before it spreads to his brain, but is then forced to coexist with the mutant creature when it takes control of his right arm in “Parasyte.” Part horror movie, part buddy comedy and part superhero origin story, this clever twist on the classic body-snatcher formula.


Instead of casting an over-the-top local comic in the head, he centers the action on a relatably normal kid, Shinichi Izumi. When a shower of glowing space orbs falls around Tokyo, the gross, brain-seeking ear-worms that emerge go looking for human hosts, but the creepy-crawler that finds Shinichi is thwarted by his headphones, entering his body via his right hand instead.

Well it's literally about aliens that's supposed to conquer the world. They are disguise as a human in form by eating their hosts brain. Once they eaten their hosts brain they will start to form or imitate the hosts head and face and once they done that they'll start to take over the hosts body. But the hero named "Shuichi" has prevented the alien that's supposed to eat his brain and what the alien did was it ate his right arm instead. Shuichi and the alien doesn't have a choice but to live together cause the alien ate his right arm right? So the alien became his right arm. Then shuichi named the alien "Migi" meaning right, pertaining to his right arm. Shuichi and Migi met a few kinds(aliens) of Migi. That's when they learned that Migi wasn't alone, that a bunch of alien came here in this world, and their mission was to slaughter man kind to lessen it's population.…