The story revolves around a high school student, (Najai Kei), who died in a car accident and returned to life because he is an 'Aijin.' The Aijin are creatures that regenerate their bodies after death as if they are unharmed no matter what happens. Our hero escapes for fear of being caught and exploited to become a guinea pig, later becoming part of the ongoing conflict between the Aijin and humans, where he must choose to aid one of the sides.