In a war-torn future, a machine called the E.T.A., or Emotion Transfer Apparatus, is developed to rid soldiers of guilt and PTSD. Once Ajin gets his hands on an illegal version, he modifies it to amplify the user's pleasure with the dream of selling it to make a fortune. When the military gets wind of his plans and captures him as an adult, Ajin unexpectedly reunites with his childhood friend, Hyeon, who is now a military officer. Believing Ajin abandoned him when they were young, Hyeon is hellbent on getting revenge by using the augmented E.T.A. on Ajin himself... (Source: Tappytoon)