To be honest, I was kind of disappointed with this drama, because with such an interesting main story they really didn't do much to develop it. That being said, I think Oh Ji Eun did a pretty good job acting as Ha Sun Woo and Han Na Young. Each mystery was interesting enough to keep me watching every episode and even though some were really good, there was a certain point in the middle of the show I started to get bored, because at times I felt like I was just watching filler (Han Na Young getting jealous and wanting to go shopping?) when they could have been developing the main story. They just kept on showing the same ol' flashbacks for the longest time. The last few episodes were pretty good, but I didn't really like (or get) the ending. I felt there were too many things left unexplained, such as his power to use his blood as a weapon against demons, how he got the blade, and more about his old partner. Especially since, I mainly started watching for Baek Sung Hyun (who did a pretty good job playing *****)