Title (4/5):
While the title does relate to the story and is even used in the foreword, I don't know if the story's title is really unique. It doesn't seem like it's very original, which isn't always a bad thing, I just don't know how eye-catching it would be either. I feel like this is one of those hit/miss titles but who knows. I do think it's good that it relates since this is an unexpected journey indeed.

Description/Foreword (6/10):
While Korea and Japan are nice places to vacate at, you should never ever ever go to a country trying to meet a band which is kind of what is implied here. That's a lowkey point of stalking. I've said this before but if someone does want to go to a country to see a band, I think they shouldn't go at all. That's the impression the first part of the description gives off. In truth, I think the first part of the description can be deleted. The second part leaves more mystery to the story and doesn't make the OC seem like a stalker. The foreword is fine as is.

I don't know how compelling the description would be but as of right now, I wouldn't be compelled to read it merely because it seems like she is travelling to these places HOPING to meet BTS which is no-no. I'm planning a trip to Korea because I want to learn the way they function since I plan on living there for work, not to try and meet idols. so without the first part, I think it'd be a better description.

*Plot (10/50):
The plot is very illogical and unrealistic. It's just not something that could ever happen to anyone, no matter how sincere they seemed

BTS would not randomly start talking to someone that is staying in their hotel, that would compromise their security and truthfully, someone would have found their hotel location out because it's happened so many goddamn times in various countries it's almost a joke now. They definitely would not invite a stranger to eat with them, I think we both know that by now. You can't trust anyone when it comes to idols, especially with the amount of hatred BTS gets as a whole. The managers wouldn't have allowed it either.

You never know when something could happen, just like that time someone tried to give EXO's Sehun something that would have probably gotten him sick or even worse, fans told him not to eat anything he was given and I'm sure we all know why.

If this was an AU, then maybe it'd be more logical since they wouldn't be a famous band but as this isn't an AU, I can't see it being true and this kind of stuff is quite cringy to me since I think people need to not go places with the hope of meeting a band in mind UNLESS you are going to the country for a concert which I know many people do since certains bands don't go to their countries.

I just feel like this story is too illogical for me to enjoy since it's supposedly in real time, not an AU. Not only that but this plot has been done before and I've seen it on this platform over the years which makes the plot kind of generic.

But now for the main question. What's the plot's conflict?

I don't see any conflict as far as we go. The conflict cannot be her going to Japan and meeting BTS, that is not a conflict. If that was the case, the story would be over since it'd been resolved by the second chapter really. Every story needs a strong conflict because if there is not one, what's the point of the story? The story usually ends after the main conflict is finished but if there is no conflict, where will the end come? Now, the conflict may not be obvious until later, but as of right now, there doesn't seem to be any conflicts.

To improve the story, you need a conflict. Without it, there is no point to the story. It's just there. I think you also need to really take the time to talk about things instead of simply rushing into it.

As a reviewer that's been doing this since 2013, you really tend to notice things more than a regular reader who hasn't reviewed a single story in their life so not many people would question why this story is there and what the conflict is which is why reviewers are there. Reviewers tell you things readers usually won't which is why I'm saying the things I am. 

Overall, the idea is quite cliché and, sadly, overdone. The conflict is not very clear as of right now and whether or not that changes does depend on you. I don't really see anything in this story that makes it stand out from the other stories like this one. I won't go searching for them but because there are a lot of stories on this website that'd be impossible. Not only that but the plot is very illogical and unrealistic and just doesn't give the best of vibes, I feel like these stories sometimes support the idea of going to a country to see idols and hoping to get the same hotel as them which is beyond creepy and stalker-like. I'm not saying that is what you wanted, I know it's not, but that is the type of vibe these stories can give off.

*Writing Style/Flow (6/20):
Main problem is the story started off in third point of view and switched to first point of view. This is a no-go for writing, you should always stick to one point of view because changing it is just... not good.

It starts off by using "Pia" (3rd point of view) and then changes to the use of "I" (1st point of view) and then it's back to third point of view. Stick to one or the other (third is usually the better one to use).

Also, I don't know if you understand the term netizen. A netizen is a user of the internet, people who are avid users and they (usually) use it properly and responsibly. I think the word you meant to use were citizens considering people of South Korea are Korean citizens or South Korean citizens since they live there, they are not called netizens, they're citizens just like anyone else.

Moving on to grammar in general, there were some issues here and there with the grammar but I do think you told me English wasn't your first language. I'll point out a few things I noticed.

1. Run on sentences.
The first paragraph was a bit of a run on sentence.
E.G.: 18th birthday is a pretty big thing in their cultures for girls, so rather than having a debut party which will be a flop since she doesn't have those many friends to fit the 18th members in each category for the party like candles, roses and such and besides it will be a hustle on thinking of a theme of the party which some of the guesses won't dress according to the theme.
There is a lot wrong here. Commas are missing, sentence needs to be cut down, some of the words used are strange or do not fit and so on. I'm going to edit the sentence and all changes whill be marked in red.
Fixed: In their culture, the eighteenth birthday is a pretty big deal for a girl but rather than having a huge party, which would be a flop since she doesn't have many friends, she decided to travel to South Korea, a place she's always dreamt of visiting. 
I shortened the sentence greatly because there was a lot of unneeded words there such as the talk about candles and... the wearing of dresses and themes. Most people know how parties work so it doesn't seem necessary to add the stuff in. Not only that but the way everything was worded was hard to really understand. I changed the word debut to huge because what's she debuting into? Not a band surely. There was a few missing commas, which I added, and I combined the last sentence to make it one whole sentence that got straight to the point.

2. There's missing commas.
I talked about this above as well but here and there, there's missing commas which can create a run on sentence just like the one above. I'm not the best at explaining this stuff but I have found a website that you can take a look at that may help with commas and when to properly use them. 

3. Misuse of commas.
Just like above, there are some sentences WITH commas but they aren't used correctly or they are used in a way that is odd sounding.
E.G.: She took a deep breath and look at the surroundings still, cannot believe that she is finally in the country that she wants to visit the most.
The sentence is odd because the comma makes it seem like the sentence is cut off. There are also some grammatical issues but I'll fix the sentence and explain why.
Fixed: She took a deep breath and looked at her surroundings, still not believing that she is finally in the country that she wants to visit the most.
There are some problems with tenses and such but I'll get to that next. When you placed the comma after still, it's like the sentence has a pause which makes it sound weird. Commas can indicate a change in tone or a pause in a sentence, that depends.
E.G.: That's a persian, [small pause] a type of cat, [small pause] isn't it cute?
So what your sentence sounded to me was like this. "[...] look at the surroundings still, [small pause] cannot believe [...]" which sounds quite odd. Not only that but since the word 'not' isn't there, it's almost like a word was skipped over. This is the best way I can explain it since I at explaining things so I hope it made some kind of sense.

4. Tenses.
Using the sentence above, the one I hadn't fixed, we will talk about tenses.
E.G.: She took a deep breath and look at the surroundings still, cannot believe that she is finally in the country that she wants to visit the most.
The problem are the words 'look' and 'believe' as they are in the wrong tense. While this is present tense, it doesn't work for this sentence. Like the fixed version above it would be 'looked' and 'believing' because she looked at her surroundings.
Another possibility (it doesn't work for the sentence I fixed but could possibly work for the one you used) is 'looking' because she was technically looking around. "looking at the surroundings" but this would only work if the sentence was fiddled with. 
As for believe, in the sentence I did (fixed version) it would be believing. "still not believing" because she couldn't believe where she was. But, you can also use believe IF the sentence was: She could not believe. I hope this made sense, just keep in mind tenses and what endings words should have when using them.

5. Adding punctuation (periods, question marks, etc.) before closing off dialogue.
This does happen a few times within the story so I figured I'd point it out. 
E.G.: "Good evening" The man with the blonde hair greeted her in English.
Fixed: "Good evening." The man with blonde hair greeted her in English.
You could technically also use a comma but in this situation, a period is more appropriate. If a character is going to continue the dialogue after the first set, then a comma would be used.
E.G.: "Hello," the man with blonde hair said. "How are you?" 
I gave an example because I figured it'd be easier to show it rather than just explain it. 

6. Whenever using an "I", you need to capitalize it.
You did capitalize a few "I"'s but there are also a few that are used as "i" which is a no-no so I would just be more careful when using the term "I". 

7. Lack of details.
There is a significant lack of detail here. Example would be her time in Korea. To map out the first chapter: She is with her mother at the airport, she gets to Korea, small detail on what she does, and then she's in Japan, at the hotel she runs into a BTS member already. This is very very rushed, there's no details on much of anything. Also, instead of calling BTS by nicknames such as 'Hobi', you should probably stick to using their real names.

The flow of the story is almost scattered. You barely talked about her time in South Korea since... BTS wasn't there so it was almost like going to Korea was nonexistent in the story since she gets there, not much is said about Korea, and then she leaves for Japan. I think this brings back what I said before; do not go to a country because idols are there. That is considered stalking and BTS/BigHit would not appreciate it.

Moving on from that, you should take the time to develop her character, which I'll talk more about next, instead of rushing into things. It makes the story seem very rushed and scattered. The story seems very unplanned as well, maybe take some time to really plan/map out what you want to happen in the story. It helps A LOT trust me, I do it for most of my stories now and if I don't, I end up being VERY unhappy with what I wrote. So planning details, characters, etc. will help in the long run. 

Characterization (3/10):
I feel like Pia is someone I'd hate in real life to say the least. I don't like people who want to go to countries to meet a band (or have the hopes to meet a band) because that's not humane and the band wouldn't like it. It's like the time BTS had to run away from 'fans' in a country where they wanted to relax and be on vacation despite telling them that they wanted to be left alone. Both Japan and South Korea are nice places, I've seen photographs and movies but for some reason, because of K-pop, more people want to go there in hopes of seeing idols which is illogical and very childish. That's the kind of vibes I got from Pia from the first chapter and that kind of stuck throughout the whole story. She's not very special as a character either, she's like a lot of OCs out there. Her personality isn't very special and I just.. she's kind of flat. If you compared her to other OCs in these stories, they'd all be the same generic characters. Also, we know little about her. I don't even think you mentioned where she was coming from directly. You mentioned PH but it doesn't take 12 hours to get from Manila to South Korea, it takes like 4. 

BTS's personalities, just for the fact that they even invited a stranger over, are not very accurate. When writing stories in the idol universe, I usually think that people should keep true to who they are as people and not be reckless. This, in truth, was very reckless and I'm sure the managers were there with them somewhere so I don't think they'd be allowed to start hanging around a girl especially one that is a fan just for the sake of risking the band security and even the females security because we both know how stupid A.R.M.Y's are for the most part (don't get me wrong, I'm one as well but... let's be honest here, I've seen enough on Twitter to know how stupid this fandom can be) so for this, I don't think I like BTS here considering how illogical and how far off they are. 

Overall, I think characterization is lacking a bit here BECAUSE the story was somewhat rushed in a sense as I said above. You should always take the time to develop characters but there's not much said about Pia as a person, she just comes off as a bit of a creep at some points. The flow of the story CAN impact the way characters are presented which is not a very good thing. It's like the butterfly effect, flow can determine how characters are and how well they are presented.

Personal Enjoyment (1/5):
There's a lot of reasons I don't enjoy these kind of fanfics and the main reason is because of the fact that they seem to promote the idea that it is okay to go to a country to try and see idols or to get the same flights as them and so on. BigHit has expressed a severe dislike for these things and I just don't see why this concept is a thing, if you understand me. Don't get me wrong, I understand that fanfiction is supposed to endure 'fantasies' but I just feel as if these promote the wrong idea. Sometimes fanfics can impact people especially if written by people with 'followers' (I don't really understand this since... fanfic writers aren't actual authors in a sense of publishing books) but that's just my opinion. 

Total (30/100):
I don't like grading reviews because I always feel terrible if the grade is low. Like, I really do for some weird reason (maybe because of when I was in high school, I always felt bad about low grades I got) but I'm here to help you, not hurt you.

I think the best way to look at it is the fact that criticism is what helps people grow, we get criticized a lot in our lives and whether we take control and learn from the criticism depends on the person. One bad review shouldn't stop you from writing or anything of the sorts because it's here to help you improve so that next time, that grade will be higher. If that was the case, I would have stopped writing a long time ago because I've been criticized as well but that helped me become a better writer and I'm still improving almost nine years later. 

So I hope you don't take this a failure, take it as the next step to improvement. If you have a positive outlook on things such as this, you will improve easily. It takes a bit of criticsim to give you a boost, I would know since I've even been criticized as a reviewer but it was in a bad way from people who weren't happy with the reviews I gave which is funny because I didn't write the story, I just gave honest opinions and ways to help fix them. But I assure you this is trying to help you. Keep this in mind!

Don't forget to credit the review shop and if you have any questions about the review, writing, or anything really, I'm always around to help you out. :)