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.' Aijin are creatures that regenerate their bodies after death as if they are unharmed no matter what happens. Consequently, our hero fled in fear of being captured and exploited as a guinea pig, later becoming part of the ongoing conflict between Aijin and humans, where he must choose to assist one of the parties.