I don't know why but before watching the drama I had a feeling that I wouldn't like it very much, and although I tried to watch it without prejudice, my suspicions were confirmed. I really like Park Shin Hye, she is one of my favorite South Korean actresses, and I adore all her work, in general, but without a doubt of all the series where she has worked and that I have seen, this is the worst. One problem is the story: a story that is not very original, in terms of the theme of the time travel of a warrior from the future to change the past and thus avoid a war that will turn the future (the present of that female warrior) into an apocalyptic hell ... If we change the sex of the warrior, does anyone know "Terminator"? Being a recurring theme, at least it had to be a very interesting and exciting story, and it honestly wasn't. It's not necessarily a bad story, but it's not interesting and gripping enough either, it doesn't really get hooked. And in the end, it gets kind of boring, with a loop that pretends to be exciting and becomes irritating.

From the point of view of the realism and the coherence of the science fiction of the story, everything was handled pretty badly and it doesn't really work if we did use a bit of logic. There are many contradictions, gaps, and unanswered questions in that chaos of changes in the past and the changes that are supposed to cause in the future (and therefore in the present). An example is a scene near the end of the last episode, in which a last-minute villain threatens the male lead with murdering the female lead in front of his eyes if he does not finish the process of creating the time machine. But at that point in the story, he could save her simply by standing idly by, refusing to finish the creation of the machine, since then it is assumed that there would have been no time travels, and thus she would have stayed safe in the future. In that case, she simply would never have been there to be shot. However, incomprehensibly the male lead gives in to blackmail in principle ... absurd things that deprive of credibility the premises of the plot.

Another big problem is the character of the male protagonist, a hateful and tedious character, without charisma, boring and unfriendly, who only manages to annoy or produce apathy. It's probably not the actor's fault, at least not totally (although maybe another actor would have worked better), but the writing. And along with this is the problem of the utter lack of chemistry between Park Shin Hye's character and the male lead character. He is undoubtedly her worst co-star in all dramas. Such a bad lead couple, I really preferred her to be alone or with almost any other man. Therefore the romance did not work out here.

What partially saves the drama is the part of the action scenes, if it weren't for the action the story would be a disaster. And the excellent work of Park Shin Hye, her great performance of a warrior from the apocalyptic future, at the same time with a funny and sweet touch (as the girl who could not live her adolescence normally due to the apocalypse and therefore is still partly an innocent female teenager despite being a killing machine). In addition to her, the actor who played her father did a great work (the chemistry between father and daughter was better than hers with her romantic interest) and there were also other characters that were funny or charismatic like the mobster who owns the store that went from being an antagonist to an ally. The villains were mediocre, irritating, and without charisma, particularly the main one of them. Ultimately, if it weren't for the action (particularly Park Shin Hye's action scenes) and a certain touch of comedy (very little) at times, the series would be totally unsuccessful. The ending was disappointing because it was not a conclusive ending, in particular, a story like this should not leave the door open to another season (although highly unlikely) and should have definitively resolved the narrative arc. Final judgment: score of 7 out of 10.