17-year-old Shinichi Izumi lives with his mother and father in a quiet neightborhood in Tokyo. One night, worm-like aliens called Parasytes invade Earth, taking over people's brain's by entering their ears or noses. A Parasite tries to enter Shinichi's ear while he is sleeping, and fails as Shinichi was wearing headphones. But he enters his body digging into his arm and seizes his right hand which is renamed Migi. As Shinichi was able to prevent Migi from continuing is journey into his brain, both beings retain his intellect and personality.
