Kiseijuu: Sei no Kakuritsu

Parasitic creatures of unknown origin descend on Earth and enter human bodies through the head, consuming the brain and taking complete control. One parasite fails to reach high school student Shinichi Izumi’s brain and becomes trapped in his right hand instead, creating a new being Shinichi names Migi.

Neither can remove the other, forcing them into an uneasy coexistence despite seeing life in completely different ways: Shinichi sees people, while Migi analyzes organisms with cold practicality. Other parasites soon discover their unusual partnership and consider them a threat that must be eliminated. Each confrontation changes Shinichi physically and emotionally, until a troubling question begins following him: if Migi is slowly learning something about humanity, how much of Shinichi’s own humanity is being lost in return?