I wanted to give this series at least a 5, there are some concepts and ideas there that are interesting but they're so massively underused or the direction they took was so amiss that writing this review I just couldn't bring myself to. Also taking into consideration I found myself fast-forwarding moments and at some points even nearly falling asleep.

In things I liked there was the fantasy element between younger and older FL as well as the bits of social commentary relating to age discrimination in both groups. The struggle of the FL in the beginning was relatable at times and I was interested in seeing how the story would unfold. The disappearances of the people in the past were also an interesting plot and although the murder mystery was kind of cliché in many aspects from the very beginning it could have made for an interesting plot anyway if they had bothered to properly work on it. Lee Jung Eun's character as Im Sun/older Mi Jin was also the best of the show.

The main issue with this series is the fact that it feels they didn't bother with anything enough to make it stand out in any way, in fact it felt they wanted to make it so plain and average that they ended up not having enough plot to cover the whole of the episodes and as a result it's very dragged and many episodes are very uninteresting, I found myself fast-forwarding bits here and there, especially as the episodes got towards the end of the series. At times it felt like I was just watching FL going to and back from work with the little bells in-between for the change and not much else. And talking about the bells, what were the point of it? You can clearly visually see the change so I just simply don't understand it, and I know it's a very small detail but they started annoying me a bit as episodes passed. I think this series would have worked much better as 12 episodes, even more considering their lack of regard towards developing the story in an interesting or meaningful way.

Starting with the plot, the murder mystery is anticlimactic and pretty obvious from early on. Sadly they didn't bother in making multiple characters suspicious enough and with a possibility of two and knowing that the first one going by the clichés won't be the culprit you know it will be the second. It doesn't feel like they tried or wanted to even try to make that part of the story interesting enough, the small flashbacks of ML's past are repeated multiple times, as are the images of the aunt and so on, but they add nothing to the story, the research is not engaging nor they bring you along for it and the reveal and subsequent developments are very lackluster, with a killer that is because yes, as usual. I'm very tired of watching thrillers were the bad guys are just simply mentally unstable psychos that kill because yes and at random. It's getting old.

On the other hand the "fantasy" element is pretty pointless. It's somehow the backbone of the series but it's massively underutilised and reduced to simply FL is that way during the day and during the night, there isn't even a real exploration of why and the ending of it it's a big disappointing mess. I can't either even start to understand why she would see her older self and talk to her as if it was a separate entity in the last dream. Sure, we could argue she was talking to her subconscious or inside her mind but it's treated too much like a different person, also at the end when ML sees her under the blossoming trees would also suggest this considering FL cannot see her at that moment either. It makes you wonder then if in a way FL was possessed by her aunt more than she becoming old, but clearly that was not the case as she couldn't hear her aunt inside nor we see her aunt in her older self to start with. This actually brings me to another problem I had with all this, and it's the fact that the FL's parents don't recognise her as the aunt physically when she's older but there are other people that think she is her, it was confusing and honestly quite sloppy, as it was the fact that the issue of the parents not believing it was her could have been solved from the start by talking to them when she was Mi Jin instead of Im Sun, or strategically showing them. This could also have been applied to pretty much everyone, including the ML, what makes this hide and seek get old very quickly and makes the FL look quite dumb.
Another thing that annoyed me a lot when it comes to the fantastical element is that when she's changing the time is shown as going very fast, what was that about? They would always fast forward the sunset and the sunrise like if they don't exist. It's almost like they couldn't decide when she actually transforms nor they could bother in animating a slow transformation. The line was more clear with sunrise but with sunset is like they didn't know what to do, so they would fast-forward like an hour of time in one second and we would go from the sun starting to set to completely night sky. It had my eyes rolling.
But anyway....how is the cat even related to the transformation? Who is the cat? Was it all indeed because of the aunt? why the aunt doesn't appear at any point in voice, spirit or in some sort of clue to know? Was she actually an old Mi Jin or was she looking like how they want us to believe the aunt would have looked as old? if the aunt was behind this, why not making it more obvious and make Mi Jin transform as her, why an older her that we haven't ever even seen?
To be honest this is just one more drama in a series of others I've seen in more recent times that use some fantastical element and it's either very underused or completely a background feature. Let's stop please, it only becomes frustrating more than anything and usually they never have a conclusion for that part of the story, it just is.

I found FL's parents pretty annoying towards the beginning, very nosy, big meddlers in her life while also saying some pretty rude things to her. They got better when they became more background characters (I say "they" but here the problem is mostly the mother). When it comes to the FL, I preferred her Im Sun persona than Mi Jin and so many times I just wished they had skipped the whole "fantasy" thing and just made Lee Jung Eun the main character of the story. Mi Jin in her younger self was annoying at times and the writers couldn't decide if she was independent and strong or damsel in distress so they changed as the plot needed, at some points she would be screaming so ML could save her, at some points mostly when alone she would deal with it herself. It's quite expected also that there will be differences between the two actresses portrays of the same character but sadly at times they did indeed feel too much like different people.

ML is a character that almost feels like they wanted to make nuanced but at the same time present as the smart prince in the shinning armor. I was not a fan of him, most of all because he was very rude and abusive in the beginning of employees, very ageist as well and him looking at FL in the kitchen and thinking of his mother was kind of the cherry on top. But overall the worst for me in terms of the character is that duality between presenting a nuanced character but also giving him to me in a platter of gold like he's supposed to be a role model or a romantic interest for the viewer as well as the fact that in the end she was the reason he changed after-all what it's just not real and sends the wrong message . Sure, I'm going into details when in fact his character is not very explored but I feel it still applies. We got more insight of FL's psyche than him. I get his past is haunting him but that can't be his whole personality and even in that sense we don't get a lot of depth into his past, only the same 4 scenes recycled. His mother was clearly not great either but there is no thought, conversation or even mention on his thoughts about his mother at any point. Because of the superficiality of it all, when the remains of the mother are found in the end the scene of him crumbling doesn't have the emotional depth it should for me. People around him keep repeating how much time he has spent on the case trying to find the people but we're always told and not shown the depth of it in a meaningful way so it was difficult for me to relate. I think Choi Jin Hyuk did his best with what he had but that scene of him crumbling has more depth than the entirety of what we have been shown of him, it's very disjointed because the plot didn't care enough up to that point.
In fact, we could argue that until around episode 15 the plot didn't care much about anything and then the whole plot and reveal is dropped in a few scenes because "we got to get on with it". It's just such a sloppy execution.

When it comes to the romantic development of the main leads the plot is disappointing. It's very plain and I'm still scratching my head trying to figure out why they even liked each other since except for a few moments of revelations they didn't seem to share much. I could understand her crush on him based purely on the fact she would see him as this cool and composed prosecutor with a great job, but the other way around? We're introduced to his crush to her in a slow yet weird manner and in general it feels like their relationship is quite detached at the same time. Either way, the worst of it all is the cliché of "ending it" an episode to the end what adds absolutely nothing as always and it was awkward and very pointless. Now, if for example they had decided to go another way with solving the fantasy element of the show then it would have been more interesting he would have helped solve the mystery of it maybe.
The dynamics between them could have been hilarious had they stuck to more comedy throughout the whole series (and if he had found out earlier about her changing even) but the comedy aspect is dropped early on and then the few moments that try to be more comedic just end up being embarrassing more than anything.

When it comes to side characters Ko Won is extremely pointless and the attempt to make him second romantic interest was laughable. They actually had great chemistry as sidekicks but they obviously HAD to try and cross the line, it was very awkward, especially considering Ko Won had most of his interactions with Im Sun and not Mi Jin. Yet at the end they try to refer to it in flashback as friendship and camaraderie like if he confessing his feeling hadn't happened. Weird.
Why didn't they pair Ko Won with Do Ga Yeong? I get the not wanting to cross the line of fan to lover or something but it would have made for a cuter story in my opinion. The love story between her and Ju Byeong Deok tries so hard to be comedic relief but it was quite embarrassing and unappealing and not going to lie a lot of it has to do with both the age gap and also that Ju Byeong Deok as a character came across a bit as a perv at times in his buffoonery ways.

I'm not sure I can recommend this drama even to pass time if you have nothing to do because of how draggy and slow it is, I generally found it boring. It's watchable yes, Lee Jung Eun is great in her role, has some endearing moments of camaraderie and the murder mystery although very cliché and predictable is not exactly unwatchable, but 16 episodes it's just too much in my opinion and there are better dramas out there to pass the time.