User Not Found doesn't have a super profound message, storyline or concept per se, but it's not really meant to be that way. It's nothing new, still has the same love triangle plot line, although the love triangle isn't super strong in this one since Hyejun isn't really interested in the main Yoo Minjae. But it's still a refreshing Korean Drama and it also doesn't take too long to watch. Definitely enjoyable for times where you just want to be entertained by something sweet, interesting and quick.

I'll just go through a few of the characters:
Main Yoo Minjae: Super relatable character, I've been in the same position of going to a new school and being scared of not having friends, so seeing her be in that same situation was very understandable. She was very naive though, as is the case with most female k-drama leads unfortunately, but i'm glad she at least had Hyejun and No Min to point out her naiveté and how she shouldn't trust everyone, because Jiwan was such a snake and it was frustrating how much main Minjae didn't see that. I was also kinda scared when she started trusting Hyejun, but she was lucky he ended up being a good person at the end. She grew from that though. At the end she started seeing people for who they were and stood up for herself.

No Min: I loved how confident No Min was and how much she used her experience to see through all the fake people Minjae was dealing with. Their friendship was so refreshing and genuine. I was really curious about what happened to her, and it was really sad what happened, but at least she got to get a bit of justice.

Yijun: I hate to say this but he was really boring. I'm just not into the whole quiet, misunderstood, kind male lead thing. I'd much rather have had Hyejun as the male lead because at least he had a personality, and although he was twisted, he was still interesting. Yijun was alright though, at least him and Minjae had similar interests and he was nice.

Hyejun: I liked his character development. At first I really didn't know what his intentions were, I thought he'd cause problems for Minjae, then realized he just needed real friends and was actually very caring. Although he did some messed up things, his intentions were always good. I think him and Minjae would have been such a cute couple. He was so much more attractive to me than Yijun, him and Minjae had amazing chemistry, he was smart, and he knew her secret from the start.

I would probably not rewatch User Not Found as it's not something I loved, but i did really like it and thought it was very wholesome. The ending was kinda rushed, and it wasn't really clear to me whether they exposed their real identities to their classmates or not, plus I didn't understand why No Min didn't expose her ex, but I liked how Minjae and her gang ended up being genuine friends at the end. 8/10