First for those who've seen my list, yes I'm bad at giving rates, but for this drama I genuinely want to give it a 10, I just loved it so much, which is also the reason why I wrote this review for it.

I should start with saying that this drama is not for everyone, its very complex and confusing at times. Its also an R-rated drama with some 19+ rated episodes and it can take an emotional toll from you, so do take this into account before watching.

Story
I watched the show from the start when it was streaming and I must say I never could wait for the next episode, which is a good sign as it means I was very intrigued by it. As I said it can be confusing and complex at times, but for me this only made it better as I loved to speculate, theorise and read theories from others. There is a lot of mystery in the drama, but I've to point out that this is not a mystery thriller. So certain things may seem quite predictable, but thats because its a psychological thriller that focuses on the characters and emotions. Certainly the first part of the drama can be a bit misdirecting about this. The drama contains also a lot of twists, at certain times I wasn't sure how they were going to stretch the story till episode 20, but the twists always surprised me and eventually I didn't find the drama stretched at all. Important to mention also is that there are certain things in it that are still considered science fiction. Personally I didn't mind this, but I saw a lot of people who had problems with it. My advise is even if you don't really like this, don't give up immediately it's not as problematic as it looks at first. And for me it made the story all the more interesting and actually quite unique. There is also minor romance in it, actually more than I expected for a drama like this. For those who don't like this don't worry it doesn't feel out of place and it isn't cringey at all. I actually really liked it, but of course also don't watch it for a happy romance. Finally the ending is very satisfying, which I was very happy about as a lot of good dramas have a problem with the ending.

Actors
This was my first drama with Lee Seung-Gi and I must say he did a phenomenal job. It does take some time before he's able to show his acting skills, as his character only becomes more prominent and complex later into the drama. So at first he may not seem that impressive, but later when he's able to he's fantastic.

I loved Lee Hee-joon, I had seen him before like in "Legend of the blue sea", but although I like him there also, it was here that I was very impressed by his acting skills and became a fan of him. The way he was able to portray emotions was phenomenal, he certainly deserved the nomination he got for his acting skills here, really hope he wins next time as he really deserves it. I really can't wait also to see more of him.

I loved Park Ju-hyun also, she's actually the reason I found out about this as I was looking for other dramas with her. As always she did a fantastic job and I'm certain she will become a big star if she continues to impress like this. Not everyone seemed to like her character, although this is a minority and mostly I found the reasons they had for bashing on Bong-Yi quite unreasonable. I've to admit I also hoped that Bong-Yi maybe had a bit more prominent role and maybe I'm a bit biased about her, because I really like Park Ju-hyun. But overall I was really satisfied, really loved the character and felt quite an emotional connection with her.

Like many other people, Kyung Soo-jin character was probably my least favorite of the main characters. She also did a really great job and it's certainly not that I disliked her character, but I guess I just felt the least connection with her character, which isn't her fault. I liked her the most in the beginning of the drama, but later on she disappears a bit to the background, which is probably the reason.

I really liked the rest of the cast also, certainly Kwon Hwa-woon and Ahn Jae-wook. And the acting of the famous child actor Kim Kang-hoon was very impressive to say the least.

Music
The music was great and certainly did set the tone of the drama. I absolutely love the instrumental song at the end of every episode. I'm also very happy that they released most of the instrumental music, as they often don't do this. The vocal songs were also great, certainly "It's alright" and "Too late".

Overall this drama is a must watch, although it's not for everyone, so do take some of my points into consideration before watching it.