Shinichi starts as an ordinary kid with a parasite in his hand instead of his head, and the show spends 24 episodes asking whether that accident made him less human or finally showed him what human actually means. The body horror is real, the action is violent, but what destroys you is watching him choose connection over survival, over and over, while everything around him proves connection gets you killed. By the end you realize the show was never about monsters wearing human faces, it was about a human learning to wear his own.

Worm-like alien parasites arrive on Earth and seize human hosts by boring into their brains, then reshape their bodies into lethal forms to prey on people. Most hide behind ordinary human faces. Shinichi Izumi, a high school student, is attacked by one of these creatures, but it fails to reach his brain and settles in his right hand instead. The parasite, which he names Migi, cannot move elsewhere and depends on Shinichi to stay alive, so boy and alien keep separate minds and share one body in an uneasy partnership. Other parasites see Shinichi's intact human brain as a danger and come after the pair. Driven to fight creatures that feed on people, Shinichi turns to Migi for help, and the two slowly grow closer as they struggle to survive. A sci-fi horror series with action and psychological drama.