Part from the title, that is actually kind of odd, the main concept of this drama is interesting and entertaining. The first episodes, however, are a bit of a letdown. The going back in time through an alien manhole wasn't executed well enough and it ended up being a bit idiotic. Plus, the story hadn't developed yet and frankly everything seemed confusing and tiring. The drama picked up after episode five or so. The story tangled up and got messy, but at least there was some progress and the main character had some development, as well as his understanding for his friends and his relationship with them. The side stories took the lead at some point, which wasn't that bad as they were interesting and entertaining. However, in the end they weren't concluded well enough as the main romance did. Now, the love story was good and the chemistry between the actors was there sometimes. In addition, the performances were really good, and they helped a lot with the progress of the story.