It has good premise but lacked what it needed to grab my attention. I didn't watch the drama with dying anticipation for the next episode. Maybe because it only has 12 episode, there too much information to cram in (500 years is a lot to cram into 12 episode) so the writer has to pick and choose what makes it. In the end, i didn't care much about their backstory, it wasn't developed enough for me to buy into it. This drama would have been much better as a seguek instead of flashback.
All in all, this was a drama I watched to kill time and not one i will remember in 2 weeks.