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Reality applied unevenly in the story
There has been many many great reviews of the story, so I will add only one that I have not seen anyone mentioned.I agree that what happened to the main couple, and even the Class President (sorry, can't remember the name) are realistic. Those things happen in real life, even though we don't think great love like that of Baek Ji Yin and Na Hee Do should be like that. However, they are still just young adults. They still have so much to learn and grow.
However, my quibble is with the unrealistic achievements afforded to Yurim and Ji Wong. In real life, people with limited resources, as Yu rim's and Ji Wong's background were depicted, face a lot of obstacle when starting their own business. Passion and skills alone are not going to be enough. Funding is a big one. I can see that Yurim has a better chance to open her fencing school. However, given Ji Wong's family circumstance, where did he realistically get the support and resource to start a company that can buy and sell high quality products? The story would have been much more in line with the desire to be real if Ji Wong had a thriving blog but not a CEO of a successful company after 7 years.
Does it sound like I am salty? Yes, I am. :)
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realistic story
i crying over this best 2022 kdrama ever, i can't move on even after months and never rewatch cause this "congratulations on your wedding" traumatized T_______T but i like kim taeri, bona and nam joohyuk's acting here hoping next project for both of them. my fav scene is when baek yijin break up with na heedo thats hurt so bad and i got a moral message that what is forever close to us may not necessarily be together. even i totally agree that na heedo husband is not published because it will ruin the expectations of the audience including me, better not to know.Was this review helpful to you?

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You must watch this drama!!
This story will get you immersed. You'll laugh, cry and be with them until they reach their own dreams. Main cast and other casts are all good actors. They really showed the right emotion every scene that they are acting. One of my fave scenes is when Baek Yi Jin had to sub for the guitarist during the school festival, I feel the scene when Na Hee Do looked at Baek Yi Jin during the stage and Baek Yi Jin smiled and looked back during his times. AAAAAAA I love them so much, all scenes are worth watching! I will never forget the bus stop scene, I cried so much and so many thoughts kept ringing on my head. Also the Full House scenes, fencing matches, beach trip and the nostalgia from 1998. How they meet and how they progressed, the scenes from the tunnel!!! I learned a lot and I relate so much with this drama. I hope you watch it too! :)Was this review helpful to you?

A little jewel
I am truly in love with this drama. And for people who are used to my comments, I never say this.The thing is, everything about this drama is so poetic and gives you a nostalgic feeling even if you never lived in Korea at that time period or even if you were too young (or not born) to remember how the end of ghe 90’s and beginning of the 20’s were. In that, the drama is very strong.
I won’t say much about the performances, everyone is on point, they don’t over do it and don’t lack in any way. You get attached to all of them. And again this is how strong the drama is.
The cinematography, the music everything is very poetic to me.
What I like the most is how every details matters. Who knew there was an old korean song holding all the meaning of this drama and its ending before you reach it ? And the directing is giving it to you.
If I had to point out one drawback it would not be the end. As I said, if you are ok with the meaning of the song (same name as the drama for thos who don’t know) and the fact that the drama is a time traveling to a forgotten time, the ending is good. So the only drawback I have is the Na Hee do as a mom and the teenager Na hee do are too far apart to me. Of course we all grow up, get wiser blah blah blah but to me there is absolutely nothing similar to old versus young Na Hee do… and it should be important. As we are opening and ending with the old Na hee Do (sorry spoiler), we want the young one to make that bridge that will connect each other and it is missing. I think it was a cast problem.. (maybe).
otherwise, great !
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First Love
The title alone should already warn us of the ending but some didn't take the hint.Likes
1. The friendship between Heedo and Yurim was my fave part. All their final matches and when Heedo retired 😭
2. Heedo and Yijin's relationship. It was the right love at the wrong time. Maybe if they met in their 30s they could have handled the relationship better.
3. Yurim and Jiwoong's happy ever after is a contrast to H&Y. Despite the LDR they still made it work. Maybe coz they didnt have a lot of issues to deal with.
4. The fashion, the music of the 90s I can relate.
5. I love sports themed dramas so i love watching all the fencing scenes.
Dislikes
1. I think the present timeline wasnt necessary. Maybe because they used a different actress to play Heedo and she had a very different vibe from the younger Heedo. It makes you think what happened to her all these years and how her youth and passionate love shaped her into who she is now but we didnt get any of that. Instead I felt like she only had closure when she found her diary. Who did she marry and was she happy?
2. We also dont see what happened to older Yijin aside from being UBS anchor.
3. I didnt mind the ending, just wish it was stronger and made more impact. But otherwise this was almost perfect.
Rating: 9/10
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I hate to love it
I am absolutely livid at how this show ended. This was one of the best love stories I've seen in a kdrama in ages. I haven't felt so captured by the two lead's emotions and the story as I did in Twenty-Five-Twenty-One and it hurt when you find out that they didn't end up together. The actors and story did such a good job in making the viewer believe in love and then they rip it out from underneath you. I've set the rewatch value at such a low rating because I don't think I can put myself through that kind of pain again. Like I avoid these types of painful situations in my own life for a REASON. I'M TOO WEAK AND WILL NEED TIME TO RECOVER AFTER WATCHING THIS.Was this review helpful to you?

Better Than Expected
Every so often I get this urge to binge-watch recent k-dramas and this happened to be included this time. Tbh, I'd scrolled past it for a few weeks before finally giving it a chance. Honestly I'm glad I did. The characters and chemistry was so good! I loved how everyone evolved over time and the character development. Also, let's not forget about the music. I actually first heard about this drama when it was announced that DK was doing an OST for it. It's such a good song; along with literally every other song on the sound track. This is one of those come of age, feel good type dramas. I highly recommend it.Was this review helpful to you?

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realistic, overall the drama is unique and different from your average clingy romance plot
[please don't read this unless you've finished the drama!]this is my first time writing a review and i'd like to keep this as short as possible haha, overall this was one of best kdrama i've watched. amazing plotline and again it was realistic. of course, the ending wasn't something that'd make you smile, but nevertheless it was still beautiful. it portrayed how your first love or your greatest love wouldn't always be there with you forever and how you should move on with life regardless of what happened in the past; a lesson on life. on a side note, i've also seen people being confused on who heedo married and in my opinion, i don't think the identify of him matters at all. i believe the writers just wanted to show how heedo had moved on from yijin and was able to live her life and finding a new partner.
aside from the ending, the overall plot is still very refreshing and is something that you'd enjoy, this drama clearly showed youth in the 1990s, as a teenager myself, this drama reminded me that i should be spending my teenage life on something fun instead of wasting time staring at a screen. moreover, the drama itself is actually pretty healing for me, (not included the ending ofc, i cried for 2 days straight for that.). the most beautiful thing in this drama is how the main leads starts from supporting eachother, being there for eachother into falling inlove. it was a natural process and not rushed at all. out of all the kdramas i've watched, i was most jealous of their relationship. even if the ending wasn't what you'd expect, they still loved eachother with their whole heart and did not regret falling inlove. meeting eachother made their lives and youth shine brighter than before, a fateful encounter.
i don't think heedo left yijin, nor did yijin left heedo. it was fate who left them.
some reviews have mentioned this before and i'd like to mention it again. the ending is what make 2521 unique from any kdramas. the writers did not attempt to force the main leads together and i appreciate them for that. the ending was probably the most realistic one. watching 2521 was a refreshing and nice journey for me. i enjoyed it very much and to the person reading this, i hope you've had a great ride in 2521 too! <3
alright, time to study for my exams now haha, again i hoped you enjoyed 2521 and have a nice day!
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I really enjoyed this drama. It felt super real and the fact that these two people who genuinely want to be the right person for each other still end up not working out, makes it more honest and relatable. I think the show does a really good job of showing that the timing can just be off, people want different things, and sometimes you just have to put yourself first even if it hurts the other person because staying together will only be detrimental to the both of you. Was this review helpful to you?
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It just felt incomplete but yet loved it
I loved this drama with all my heart and everything from the very begining. I loved how it explored friendship, goals and might I dare say love. It had everything. This series gave me butterflies and made me cry at some points. How I kept on silently rooting for both Na Hee-Do and Baek Yi-Jin. How I cried every time Hee-do won and celebrated with her friends. This series really showed how friends grow apart but still play a great role in Every step of your life. Reminded me of my college buddies and how we all went different ways and still are there for eachother always to support each other. The cast was just amazing and acting was perfect except the middle aged Na Hee-Do. She kinda ruined the character's vibe tbh. The tracks were great too. The story was so nice to watch and of course I desperately wanted a happy ending but didn't get one which was okay too. The drama really taught us that not every fluffy love story has a happy ending. I was not dissapointed at the fact that they didn't end up together but I was more dissapointed at how they ended the series without proper explanations. At some point of the drama it was indicated that Na Hee-Do didn't have much connection with her friends anymore. The show never really told anything about that later. They never showed us if they actually got apart or just weren't friends anymore. They never finished Ko Yu-Rim's story. And the worst was they never showed Na Hee-Do's husband. I really was hoping to see her husband or at least their family photo to know who she actually ended up with. And what happened to Baek Yi-Jin.. Was he married too? Ughhh so many questions and not a single answer and yet THIS is one of my favourite dramas. Netflix you owe us some answers baby. Give us a season 2 or at least a special episode or something. We really need some closures.So to summarize It felt incomplete but yet I loved it
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A very bittersweet story about love, hard work, friendships, fate and facing the inevitable. I very much enjoyed the story as it was so much different from your regular Korean dramas. The plot was very refreshing, and even the side characters had an interesting character development overall. While most topics about the ending and relationships were discussed in many of the existing reviews, I just wanted to say personally, the ending didn't work for me. Maybe it's because I had too many unanswered questions about Na Hee Do's year's leading up to her marriage and then having a daughter. Hence, I wasn't that satisfied with how the show was executed towards the final episodes.
I'd say a very good watch because of the rather interesting story and the visuals, worth the hype that it gets.
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Suggestion to watch
“Learn to let go sometimes.” both Hee Do and Yi Jin grew up, their relationship failed to grow. They expected it to stay the same when they weren't the same people anymore. Yi Jin understood this fact more than Hee Do, but miscommunication, misunderstanding, and impatience took the best of their relationship. This drama was really enjoyable and i loved it. However, in context of the story, and as substantiated by the Hwa&Dam production company, the first love of Heedo and YiJin was each other. YiJin corroborates it in the final minute of the drama: Who is your first love? Na Hee Do.Was this review helpful to you?