The TV show has no such high IMDb rating, which according to me it deserves,
Here is the reason I think so;
On an average every k drama has 12 to 16 episodes but it has only 7, that's why the makers have to reveal the mystery on it's own,
also some plots remain undisclosed.
The tv show is placed in romance category but it is missing; I think it must be placed in drama, mystery (if 16 episodes), romance angle is unclear.
Overall the show was a one time watch, after all the missing link , self mystery reveal, surprisingly I want a second season for sure, I will definitely watch it.