Some individuals undergo significant transformations, at least on the surface. If you decide to watch this film, I think it inevitably brings to mind recent movies like 'The Cobbler', 'The Deaths of Ian Stone,' and other films with unusual concepts. It certainly lacked originality, but it was cleverly reworked to achieve a different result. Apparently, it’s based on an online film/series—sometimes called a social film—and I also heard that it's quite similar to the book 'Every Day' by David Levithan. My impression is that it didn’t live up to my expectations, but it was easy to follow and, overall, I don’t think it was a bad movie. If you enjoy fantasy films, then you should give this one a try. It's a fascinating fictional film with romantic elements. That means it isn't your typical emotional Korean romance-drama, but rather explores the complications of a relationship when someone is dealing with a peculiar condition. Like 'The Time Traveler’s Wife,' '50 First Dates,' and other films that focus on relationship challenges. The first hour was quite good; everything felt self-contained during that period—from a simple introduction to some enjoyable moments, until the romantic storyline took over. The second half felt like a slog; not much interesting happened beyond simply moving forward, as if it had lost its way. During those sections, most of the scenes played out exactly as you’d expect. This somewhat diminished its storytelling strength. Given that the premise was unusual, it made a considerable difference to keep viewers engaged. > "People say true beauty lies inside, > but first impressions are equally important." Once you start watching an unconventional love story like this, you'll likely want to see how it ends. I felt the conclusion was acceptable; there were no surprises, as you could probably guess where things were headed early on. It wasn’t particularly special, but it wrapped everything up in a straightforward manner. The only annoyance is that it ran for two hours—it really shouldn't have exceeded 90 to 100 minutes. What I mean isn't about becoming bored, but rather that it felt stretched out and would have been better if it had been shorter and more concise for such a pleasant film. The actors were excellent, although the most noteworthy aspect was seeing so many performers play the same crucial role—Woo-Jin. I’ve seen numerous films with unusual concepts, but I've never witnessed so many actors—certainly more than 100—portraying the same character in a single movie. The appearance changed repeatedly, but the director did a good job maintaining their consistency in behavior and intensity to present Woo-Jin as one cohesive character. These days, there’s high anticipation for films coming out of Korea. Many people around the world follow either gripping crime thrillers or heartwarming romantic comedies from this region. When they choose to watch these movies, they expect them to be better than Hollywood or European films. From that perspective, it might disappoint some viewers, because I felt it was a great concept that became somewhat ordinary for a few reasons. If you have modest expectations, then it could make your time worthwhile. Personally, I liked it, but my only concern was the third act and its length. 6½/10

Source on TMDB