This is one of the best K-dramas I have seen. Just don't understand how this is not famous. Personally found it a lot more entertaining than Goblin and other K-dramas which to me are not worth the hype.
Check it out! It has everything that one looks for in a K-drama.

And my, the casting was perfect! I've seen the pair before in Vagabond, but their chemistry here is off the charts. Bae Suzy's character, unlike other female leads, is not a weepy, dependent victim. She's got it what it takes to make you fall in love with her conviction.

Do watch!