The main character, Siwoo Lee, lost his parents to a murderer ten years ago. Finally, he meets Jack, the killer who killed his parents, and beheads him. “It wasn’t me who killed your parents.”After learning that the real culprit is a "contractor" belonging to a group of killers using superpowers, Si-woo Lee decides to hunt down the registrants with Jack’s help.Original Webtoon:Naver Webtoon, Naver Series