Not the first drama with time travel to chase a lost love and not the best either. The first few episodes introduced us to the concept and up to episode 3 it seemed promising. The first time travel was to the past and the second one returned to the present to see the consequences of his actions. He did something minute in the past but resulted in him turning into a gangster once returned. The drama hinted into creating these radical scenarios for every round trip which sounded like fun. Unfortunately, this was a one off thing and the subsequent events were utterly disappointing. The entire plot device of this manhole was handled poorly. There were obvious coherency problems and plot holes, pun intended. I think the writer realized this problem which is why he didn't include any traveling between episodes 11-15. Speaking of which, these episodes got significantly dumbed down and became soulless and out of touch. They made the love rival blatantly bad and psycho to open the way for the main lead to have a clear black and white cut, avoiding any moral ambiguity the viewers might run across. That was the only way for the writer to glue them together without performing mental gymnastics. There were other remarks to be said about characters' reasoning, underlying theme, chemistry, side characters, story structure, and romance, but maybe on a later time.