Café Minamdang

Both feature male characters who take on cases that are normally taken care of by the police or private investigators, and solves them by underhanded means.

Beautiful drama once you get in sync with the proceedings.
Many heartwarming scenes mixed with some superb slapstick comedy.

In both of these dramas the main character is con artist portrayed by Seo In Guk. Both dramas also feature elements of comedy and mystery.

Although Abyss has magical fantasy in it as well but other than that the concept is similar. Both series has same second male lead as prosecutor and similar twist and turn!