To be honest this is the kind of drama that starts off really fresh and cool with a cool agent, but starts getting so draggy I rather wash my socks.
For the cast, I think that all the characters were all really decent and especially Park Hae Jin since I'm a pretty big fan of him. However, the main problem really lies on the female lead which is really just a walking nuisance that I simply do not understand why anyone would ever fall for. Yes, it may be her bubbly personality or whatever cuteness that is supposed to be potrayed. Most of the time when the leads get hurt it would either be her just being brainless or her thinking that her actions were even useful. At the start, it was quite obvious that she was genuinely interested in the male lead but she seems to be playing hard to get far to much needed which is what makes me question what is attractive about her. Afterwards, when agent k was exposed for being a ghost agent and that all his actions were just part of his job, she got really sad when she was the one playing hard to get at first??? ok I think that the write focuses too much on making her the cause of many troubles they face.
For the ending, it was quite expected since the male lead was an agent. So in conclusion, if u are interested in a questionable romance that has no link, chemistry, or any flow, u could totally watch it for the action and cool of the male lead. -_-