I'm actually going to copy-paste a bit of what I wrote in the topic "Best KDrama ever Top 5".
I Hear Your Voice => I love it when something is already unusual in the synopsis. Here, the main character can read minds ! It's supposed to be about lawyer but it feels more like a police drama. The plot is wonderful with a bit of humour and just the right amout of romance. Plus, and that's also why it's such a great drama to me, it makes you think about a lot of things in real life. For instance, why it is SO important for lawyers to defend their clients, guilty or not. Had I watched this drama before choosing my path in real life, I might have wanted to be a lawyer.
Pinocchio => Same producers, scripwritters and main actor as the previous drama. So it's also a masterpiece plot. A lot of people liked this one less than I Hear Your Voice, maybe because it feels kind of like a season 2. No mind readings here but the woman can't lie. It's about journalism instead of lawyers. But, again, it makes you think about a lot of things in real life. Even more so if you're from a journalism school like me. For instance, how important it is to not just blindly follow what other medias can tell, why it's sometimes more important to film than help physically... And a lot of other things. I DO think this drama should be broadcasted in every single journalism schools.
The Painter of the Wind => MOST BEAUTIFUL drama. You have to love period dramas for this one and not expect any romance. It's about a girl growing up as a boy because of her talent as a painter (girls at that time can't be official painters for the palace). Her talent lead her to dangerous situations. As for the ending, I'm telling you, do not expect romance and you'll be fine. Just consider it as friendship and mutual respect, maybe fatherly love. If you liked this drama, you'll also like Goddess of Fire (but I didn't like the ending for this one). This one is more about learning to appreciate painting of that time so I don't know if it can fulfill your requirements.