Killing Killer

Summary

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.