They do have serial killers though and here it was just a Pyscho SML and his mum doing most of the bad things.
Yes, Korea has had serial killers just like every country, like the famous case that inspired Memories of Murder. But the chances that a person in Korea is going to be killed by a serial killer is about as unlikely as being bitten by a panda bear. But they seem to appear in half the K-dramas out there because writers have a bad habit of just sticking a serial killer sub-plot into any random show, regardless of whether it’s a romance, comedy, sports competition, slice of life, workplace, law, medical, or whatever. It’s an easy way to fill out the number of episodes that the network ordered without having to think too hard.
I put up with it through 5 episodes because it was fairly entertaining. But I had to finally give up, because it makes no sense and has no connection to reality whatsoever. Also, I hate annoying and idiotic in-laws and sibling characters, and there are plenty of those on both sides of the family. I also hate serial killers being inserted into every drama. Come on, Korea doesn't have nearly that many serial killers.
Rest in peace ajusshi, my favorite Korean actor. I'm sorry that you had to suffer so much from the public for actions that in the big picture really shouldn't be a big deal. I'm very sad.