I really dislike the way k dramas start with a great idea, sometimes original, to the point that it makes you think "oh it's the first time/not often I see/watch this theme in k dramas, let's see how they pull it off", but every single time, they find ways to come back to k dramas clichés that it feels like I've been deceived. Often the first 5 episodes are good and interesting then it goes downhill because the author discards everything that make it interesting at first. Sometimes it gets so worse that you get a switch of genres in the middle of the drama, like it's start as creepy, fantasy or thriller-ish story and you were in for that but then it suddenly turns into a romantic melodrama. I'm mainly looking at Doom at your service, Tale of the nine tailed that I've watched recently that fall exactly into these categories. Goblin might be in as well but I've dropped that drama a very long time ago, but i remember it was for the plot and the main couple. Other than that, Beauty inside is the only one i remember on the top of my head. I'd wish they wouldn't use these as an excuse for their romance but rather try to develop them and make a coherent plot (with a nice worldbuilding that makes or at least a nice explanation of the things surrounding the "fantasy" element).