If you watch this drama because wanna know how FL saved her late boyfriend by time traveling, you're not gonna find it. FL traveled to the past to save Minju LOL. Both the director and writer are failed to deliver the story. Here is why:

The writer developed the story really well when Jun Hee trapped in Minju's body, but not when Si Heon trapped in Yeon Jun's. Why i wanted it to be developed? Because, when i reached 9th or 10th episode, i was sad knowing that actually, Jun Hee has been loving Si Heon who trapped in Yeon Jun's body all along. That's why, imo, this time travel is also meaningful for Si Heon, not only Jun Hee buttt again, Si Heon's story wasn't really developed by the writer.

There were some parts i wish they developed for instance; I want Si Heon, who just trapped in Yeon Jun's body in 2007, to be as crazy as Jun Hee who always talks about the time travel. I also need their lovey dovey moments during that year to develop, so that when Yeon Jun died in 2022, we as viewer will feel the grief Jun Hee experiences. Why we should feel Junhee's grief as viewer? IMO and from my POV, this time travel is to satisfy JunHee's grief, because she is able to meet someone who resembles her late boyfriend, not because she wanted to prevent her late boyfriend from dying, she's just happy meeting Si Heon who resembles Yeon Jun.

If only the writer focused on Si Heon's time travel and developed the story from Si Heon's POV started from episode 6, i think it would be so much better. Because it's gonna make sense why Yeon Jun and Junhee met in university and then they fell in love, same goes with Junhee, it's gonna make sense to us why Junhee time travel to the past and met Si Heon.. But in the end, the writer makes us think that JunHee did time travel to save Minju, like for what? She's not a part of Junhee's life in the future, she's also not a threat for Junhee's life both in the past and future. Si Heon also never liked Minju in the past. So whyyyyy towards the end of the drama, the writer focused on saving Minju????? Hello, writernim???

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Let's talk about the cast. When i watched the first episode where Si Heon, In Kyu and Minju were punished for being late. I knew right away they cast the wrong ML :p just my opinion, i have Nam Joo Hyuk in my head the moment i see Si Heon who was so friendly, cheeky and playful. Throughout the drama i was like, oh i wish it's NJH.

AHS is suitable being cold and cool just like Seo Woo Jin on Dr. Romantic (i don't watch Business Proposal, tho). Or i can say, he's kinda failed to be Si Heon, there's still Seo Woo Jin vibe on him. Therefore, as for the character, imo, there seems no contrast between ML and SML. Because SML is portrayed to be quiet and a loner.

What made me staying until the end was only for Jeon Yeon Been. Unfortunately, imho, she still looks too old for a high school student (don't get me wrong, i'm a fan of her). Compare to AHS, which all of sudden NJH popped in my mind, i didn't have any name popped up in my head as to who is better portraying JunHee and MinJu.

Speaking of JYB's acting? 8.5/10. I was in awe on episode 11 or 12 i forgot, when Jun Hee sat in Si Heon study desk, immersed in his drawing and all of sudden it took her back to the future. After few minutes, she traveled back to the past and suddenly stood then hugged Si Heon without saying a word. By the way she walked,I knew right away it was Min Ju, no longer Jun Hee, even with her gesture, she proved how good actress she is. (if you have watched 'till the end, you know which scene i talked about).

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The director could not bring the best out of the cast (?)

In ATCY mostly i'm not satisfied with Ahn Hyeo Seop acting, he's good on Dr. Romantic 2 and 3, but not here. I know he is supposed to be bubbly and friendly as Si Heon, but still no fun...

Director should be really detailed in directing the actors to be similar to the role they take part in. Until the end of the episode, only Yeon Been is the star, even i watched on Netflix she said there was line she changed so that fit with the circumstance. Showing how immerse she is in her role as both Junhee and Minju. It takes two to tango, not only the director but also the actors who are willing to do more.

Behind the scene of every drama has been my favorite since i'm in kdrama land. Because as a viewer, i learn how the director direct the drama. For instance, when i watched bts of Vincenzo, how the director wasn't satisfied with actors' intonation and gesture, she would told the actors to perfecting certain part.

To conclude, as someone who never watched the original version, this is 7.5/10 from me.