In this drama, Joon-Gi Lee's character's name is Kim Hyeon Joon and Yeong-Chul Kim's character's name is Baek San. Yeong-Chul Kim character's name was also Baek San in the drama Iris (2009) and another character's name (played by Byung-Hun Lee) is Kim Hyeon Joon.
The drama is based on the American television series Criminal Minds (2005-2020).