Trace: Kasouken no Otoko (2019)

Both dramas follow a forensic specialist with a tragic past. Each episodes focus on the case while we get few clues on main characters backstory.
Overall it has a similar tone. The cast/acting is also good. Definitely recommended to the fans of crime/investigation genre.

While the two series weren't quite similar aside from the common crime/investigation genre, there was at least one common trait. As in, the fact that both dramas featured Nishikido Ryo as an eccentric forensic officer/expert. And for people who're a fan of the actor, it'll be interesting to see how Ryo's character differed in Joker as compared to Trace.

similar in the sense that it is a crime/detective/thriller show. people are solving cases and it's pretty episodic. also, they are both pretty good and enjoyabled. 8+

detective mystery show, where the mc's are solving cases together, but one of the mcs have their own "case" they have to solve for themselves

The male leads in both are quite similar, except for their jobs. Both have experienced a trauma in their pasts which have brought them to where they are now.

Both have the possibility of romance which isn't explored but hinted at.

Forensics is a shared focus in both dramas. While "Trace" solely focuses on crime solving episode - to - episode, "I Know Your Secret" has a little bit of drama and added intrigue.