One Never Ends Until Surrender (ONEUS)

There are three members of the Assassin Elite Group, ONEUS, and Hwanwoong knows one is responsible for the death of his detective mother. Vowing to avenge her, he points fingers at Kim Geonhak, who was last seen at the crime scene. But detectives don't give away their secrets so easily, and Geonhak unfortunately slips out of his reach. Into the darkness, almost too familiar. Familiar like "Leedo", a member of ONEUS.

Photo Not Mine (duh)