Title:
First off, I think the title is very unappealing. While the story is... technically about that, it's just not something that's appealing as a title. The title is what brings people to your story and I feel like the use of the word "" could turn people away. Even I just kind of made a "the hell," face when I first saw the title. It's just distasteful to look at, really.

Titles and the front cover are usually what makes people pick up a book and I feel like this is a book that might not be picked up because of the title, HELL people wouldn't even ALLOW this to be published as a book because it would raise a riot with feminists and other people since it kind of promotes being a e for a boy band (I know this wasn't your intention but it doesn't give good vibes). 

The only tip I can really give about the title is to change it and try not to continuously say she's their personal , it makes her sound sleazy beyond belief. I would pick a title that's more subtle and doesn't hint that she's a for a boy group.

Description/Foreword:
First off, the pictures. I have said this in any review that has had pictures. Don't do them, you don't really need to. I feel like people who use pictures can't describe what the OC looks like so they need to stick in pictures which is very unattractive. In a book, you wouldn't find a picture plastered of the character - the author describes how they look, putting an image into your head that shapes the character. That's the fun part about books, everyone imagines different things but with pictures, that really defeats the whole purpose so I'd personally remove them since they cause clutter and are useless. Also, no one cares about the managers as characters so they shouldn't even be there.

Second, the description kind of makes the story predictable... there's really no point. You can kind of guess what's going to happen and that's not really fun. The story seems to be going down a path that I don't really want to delve into. Like I stated above, I feel like the story kind of promotes the whole being a e just because they're famous and pay well which is a no-no.

Plot:
The plot, for one, is kind of very unrealistic. Let's be honest now, this is just not something that would happen. They're idols, they have busy schedules and I really don't think they need a "" nor would someone actually hire a female to do that, that's absurd. Not only that, but as someone who stans BTS, it's not like them to do this thing so it's very untasteful to read. Managers would NOT ever hire a person to do this, doesn't that sound.. really unrealistic? Not only that but, there's just a lot wrong here.

I could also see some people getting upset at the fact that she's willing to practically sell herself like she's just a toy for money, which practically makes her a e - something she claimed not to be but kind of is after even accepting the job. es make money off , she pretty much does the same. No difference. So I don't see why she said she wasn't a e because she literally became one right after she said that. Not only that but a is another word for a e which is the title. When the manager said he wasn't hiring her to be a e, he really was hiring her to be a e. And when he said he would sue if she told anyone, yeah um they could get sued as well for having a e because it's ILLEGAL in South Korea. Being a e, again, is illegal in this country. That would trash the company's name and BTS's name as well. So yeah, no. 

You asked me if the plot flowed well and I would have to say no, darling, no. The first chapter is also very hard to read because nothing is formatted, it looks like a huge paragraph of word vomit. The other two chapters are formatted, it was just the first chapter that was hard to read since it was all clamped together so I would try to go back and fix that.

Another thing, I don't think fans act like that in Korea like they do in America or some other countries. South Koreans are more respectful and they wouldn't go around yelling "sign my albums", most wouldn't at least - it's seen as very disrespectful to be loud in public. Yes, they will be touched depending on the situation but it's seen as disrespectful and the idols have expressed a huge dislike for it when they're out in public. 

In general, there's not much plot. What's the conflict? That she's a for a boy band? Her mother is barely mentioned and we don't know what's going on. She immediately becomes their slave practically and there's no real background story to it. There's really no conflict to be solved and I'm sorry but it's kind of gross to think about. I really can't see this and it's just distasteful as I said before. I feel like this is going to turn into PWP ( without plot). 

Advice I can give on changing this:
We know that her mother is sick but is this really the best option to get money? No, it's not. Out of everything, you chose for her to be a for a boy group when you could have made her anything else in the industry: hairstylist, outfit coordinator, makeup artist, director, and whatever else there is, you really chose to make her that? Doesn't that seem ridiculous as this is illegal? Those jobs can make as just much money and 3K seems like too much money, I doubt anyone would offer that much to a . This would easily be found out as well, things like this DO NOT stay secret for long, they are in the public eye majority of the time. There's not a plot as of right now because her mother isn't even mentioned much, we don't know what illness she has or if it's terminal. 
Steps:
1. Change the title to something more appealing, don't use the word e/, , or anything degrading.
2. Remove the fact that she's going to be a for a boy group, it's illegal and not cute (a e is a - so why did she claim to not be one but take the job?). And remove the pictures from the description, they're not needed at all. They're pointless, create more clutter, and they're useless; all they do is show that you can't explain your character well.
3. Talk about the OCs mother (what illness does she have? can it be cured or is it terminal?), home life (is it bad? good? where's her father?), what she majored for in college (math? english? business degree? what college did she attend?), why she doesn't have a job (would no one hire her? was she not qualified? etc), give us more background on the OC's life in general. 
4. BTS are not realistic and barely resemble who they are actually from what I can tell, fix the characterization of both them and the OC, it's fairly dull in this aspect - you can't relate to anyone. You should always have a character that relates to the audience to make it more personal but there's no way for a reader to relate to them.
5. The flow needs to be re-thought about. It's too fast, you should show her trying to get a job and being denied several times so we can see her struggle. We don't see her struggle here, you immediately started the story at her getting the job for the title of , not good.
6. Think about hiring a beta. There's missing commas, weird things are capitalized, and so on. A beta can help give you ideas on what to do and what not to do and that can help your story become better. Grammar isn't really the main problem here, I think it's how everything is executed.
7. Write out on a piece of paper or something, where you want the story to go. Make a timeline, I do this and it can be VERY helpful. Have someone (beta, friend, etc.) review and let them give their opinion on it. Opinions are imporant for writing, I'm positive that authors of published books have gotten opinions from their editors (which would be considered a beta here). Authors aren't always a one man show but they do majority of the work, always always always get opinions on something.
8. The chapters are very short, I usually write 5k for each chapter for fanfics but I usually see 1k as the minimum but yours are quite short and I feel like you can't get a lot from them if they're that short. Not much goes on in the chapters either so it's hard to really get into the story. I'm not saying you have to write long chapters but chapters should always have something going on, not just pointless kind of things. 

You don't have to take any of my advice, it's your story in the end. You do what you want and I'm just here giving my honest opinion about what I've read and seen. If you take something out from this, good! I hope it can help you in the future, if not - that's perfectly fine. But please know, I'm not trying to put you or your story down, I want to help you become a better writer.

Writing Style/Flow:
The first chapter is unformatted which is problem number one. Problem number two is that there are a few mistakes and other things that I noticed. I'll make a list:

1. The use of "blah blah blah", this kind of shows that you either didn't try or didn't want to bother since that phrase is usually negative and means that the person doesn't care. Like "blah, blah, blah, whatever." It's a very dismissive tone but I feel like it's not something appropriate for a work of writing, I feel like it's a more... informal thing which writing is usually considered a formal piece of work.

2. Some things are captialized that really don't need to be, there aren't commas where there should be and some things have too many periods at the end. Changes are in red. I also removed the - in her name because I don't ever use them.
Example: "Leaving the office Soo-jin felt.... Dreadful, Gross, Broken, things she never felt about herself."
Correction: "Leaving the office, Soojin felt dreadful, gross, and broken which were things she had never felt about herself before."

3. Whenever a new character speaks, it would be a new paragraph. If Soojin speaks and then her mother speaks, it's a new paragraph. Example: "Sign my albums" and unwanted touches. "Poor bastards"
Correction:
"Sign my albums" and unwanted touches.
"Poor bastards."

4. The excessive use of "~" and letters. This is pretty unprofessinal in a writing sense and isn't very cute. Example: "Ummmmaaaaa~" 

5. The flow of the story. By chapter one, she's already agreed to be their , no fight, no background information on her or her real thoughts. Just bam, she's hired as the . The flow is just like boom, boom, boom, finished story which is not good. I think you should take some time to actually explain the settings, the people, her appearance, her life at home. Give us more information so that we can try to relate (no one would relate to being a for a boy group though) with her in the aspect of her home life, maybe someone else out there has a sick member of the family which could lead them to relate and know how the OC feels. Right now, there's none of that.

Characterization:
Everything seems off about BTS. First of all, Yoongi doesn't seem like the type to just touch someone's if he doesn't know them and who the undresses in front of someone they don't know, that's just strange and isn't something I can see someone in Korea especially, doing especially when they have a "guest" over their home. He doesn't know this girl. Second of all, they are all WAY too casual about this set up which is absolutely redundant because as someone who has known BTS since debut, this is just off to me. I get that this is fiction but the whole concept is just very unpleasing due to the fact that everything is so casual about this situation which is just... the hell? I'm almost speechless.

Also, I don't they are THAT much of pigs. Their rooms most likely wouldn't be messed up to that extent because they're barely there... again, busy schedule, they're on tour right now even, so they'd stay at hotels half of the time. Do you get what I'm trying to say here? 

The OC is not original, doesn't stand out, and will be forgotten. What I mean by that is she's not.. unique? She seems like every other OC out there (...well, minus the part about being a , not many OCs are that plus, aren't viewed in a good light). I feel like the character has zero respect for herself because if she did, she wouldn't have accedpted the offer without a real fight and even then, she should have walked out. There's not much to say besides that since it's short.

Besides that, there's not much to say really as there's not much to base off on since no one is really... talked about in the first three chapters. There's not much going on.

My main advice for this is to really think about how BTS act and come off as in different fanfics. BTS usually act the same in majority of fanfics because people like to keep them realistic, which they aren't here, like for example: Most people make Namjoon clumsy because he was labeled 'God of Destruction' but keep him smart because of his high IQ. Most people make Jin the "mother" of the group (and I can see him being the number one person to be against this set up). And so on. I'm not saying to copy other people but BTS do have the 'stigma' surrounding them in fanfics which is why they seem so out of place here.

Personal Enjoyment:
So, there's a bit wrong with this story and I feel like it's definitely not something I would enjoy because 1. I don't like OC fanfics. and 2. The concept of a girl just selling herself (this is pretty much what she did) to a boy band is quite pathetic. There are plenty of jobs out there yet she actually agreed to be a band's /e? That's kind of disgraceful and unlike BTS in general. I don't really know what else I can say here because I think I've gotten the point across? But I would think about it, really, because it's not realistic or... I don't know, everything is just off.

I'm not trying to discourage you but this isn't the kind of story I would stand behind for many reasons. It has nothing to do with the fact that the writing needs some work or anything like that but the plot... there's not much of it. Every story has potential but this needs to be improved, as can any story, so hopefully I could of helped you with this. I didn't mean to sound harsh if I did but this story does need a bit of improvement but please don't be discouraged.