I have my way of reviewing, it may be different from others but hope you will understand it. I will be discussing and talking about the different sections, then will give the results :) Also, I am not one of those PERFECTIONISTS, so I don't say 

eg. "I really didn't know why he'd do such thing to me, just because of 'that'!"

I won't say "Please be specific!" Because this is clearly COMMON sense~ Either the reader has already read what 'that' is or you'll just have to keep reading!

Also, I don't go on about whether you have the foreword/description in the right box, the information provided is the important part!

Anyway, back to the real topic, here's your review. ~ :)

Okay, firstly I want to talk about the

Description and Foreword.

Good that you stated what it was rated for, to show the readers what they're are actually reading. :) 

Now, ""You,Lee Jennifer,is a good fighter,good  back talker/ talker...ect anything related for gang issues you are good at it."" (copied that from your story, I hope you don't mind )                                                                                                                                              (to) [I don't know how you're saying this, but I think 'to' would be better]

With that ^ I thought that you didn't add spaces between the punctuation and the next word just there. You don't do it 24/7 but to be honest, you do do it quite a lot. I'm not saying you should go back put a space on EVERYTHING, just so you know, try not to do it often next time :)

Then through the whole descripition, there are a few words that need a 's' at the end of them, such as brother [Thanks to your 4 brother, Chunji ----] It's more than one, even though you already said there are four of them but you still need the plural :) You probably didn't mean to?

But,Infinite doesn't know that their members have brothers from the rival groups and so do Teen Top.

                                                                                                                                                                                                                                                             (^neither) 

'So' doesn't make sense because you already said that Infinite don't know, then you said 'and so do Teen Top' <----Do you see what I mean?? o_O?

They sisters is also in good terms with both gangs.

(^Their sister is)

Probably a typo, but if it's not, you can either type 'Their sister is---' or 'Their sister's also---] sister's means sister is. Since you already added a is in your sentence, you don't need to add a 's' at the end of sister.

but when she is angry,you are very angry and is best that you stay out of her way

^This is a part from what you typed in the foreword. I kind of understand what you're saying, but are you just trying to say 'but when she is angry it's best that you stay out of her way' or maybe did you mean 'but when she and you are both angry it's best that you stay out of her way.' You should change it a bit :)

Does not love any of Jennifer's brothers or their gang  

I get what you're saying but it would sound better if it were like this, 'Does not love any of Jennifer's brothers or anyone from their gang.' :)

Nam Woohyun:1st Brother.Very kind and nice when comes  it   to you

                                                                                                                (^it) 

And again there a just some little typo's and same problems like I stated above.

Chapter 1 and So on

"Aigoo! My sister is so cute."I looked up and see somebody looking at me.It was Woohyun oppa.

                                                                                   (^saw) 

You typed 'looked' which is past tense, so therefore the rest of the sentence should be past tense too.

When I came out,there was a delicious breakfast calling me.

Again, I understand what you're trying to say, but it should be 'When I came out, there was a table of delicious breakfast calling for me'

Once we reached a corner of school but not in school like outsaid a corner,we both parted ways.As soon as I left him as he reached nearer to the school,I could hear faint screams from where I was standing.Must be thoose obsessed fangirls.Yes I know,I am so smart.

This part you needed to cut down, to me it was like 'why use gazillion words when you can cut it down into simple sentences where people can still understand?'

Something like, 'Once we reached a corner outside of the school, we both parted ways. As soon as I'd left him and he'd entered the school, I could hear faint screams from where I am. Must be those obsessed fangirls, yes I know. I am so smart.' <----- What do you think?? :)

The rest of the chapter doesn't have major problems, just the ones I've already stated.

"Anyway,we didn't lost.

                                 (lose)

*Uh-oh.This is not getting to be pretty*

                               (going)

You could see that Sunggyu was still fuming because there wasn't time to make other dig at Teen Top. (what is that suppose to mean??? O_O?)

Okay, I won't talk about everything because that's just silly~ This will be the summary

Negative:

First, you need to put spaces between the punctuation and the next word, otherwise it looks kind of messy.

Second, typo's. I know sometimes people type in a rush for their readers to be happy and read~ But try to not make those mistakes.

Third, since English is your first language, the tense of words shouldn't be a problem for you. eg. saw, see, seeing; said, say, saying. etc. you should be able to use them correctly

Fourth, try not to use a whole bunch of words not needed to describe a situation or place.

Positive:

Firstly, great that you had stated 'Rated for violence and language' so I saw the swearing coming.

Second, good character choices~~~~ (I love Infinite & Teen Top~~~ <3)

Third, the layout of your chapters is good. 

This will give the results~

[Title of Story] 3.5/5

The name of the story didn't really attract me to read it, it wasn't the name that I would click on if I were browsing. But if we looked at the characters and tags, we I possibly would~

So I give a three point five~

[Graphics] 3/5

You didn't have a background, but you did have a poster.

The poster wasn't what I thought it'd be, NOT TRYING TO OFFEND THE DESIGNER. The poster DID have the main characters though, which was good, but the poster didn't catch my eye that much.

[Foreword and Description] 14/20

Really was just the problems above :)

Good credits :)

[Originality] 4/10

Well.....I've read a lot of stories where the main girl is siblings with the gang members and so on. 

[The Plot (Flow of your story)] 10/20

Ten is the most I can give you, to be honest, I couldn't really get myself into the story and I skipped some parts. This is probably just me though, I don't really get into the story because it's a bit too unrealistic? Sure, there are SO many other unrealistic stories, but like the title of your story says, brothers in different gangs with a sister just don't really mix. It's too.....dramatic?

[Vocabulary, Spelling and Grammer] 10/20

Okay I'm going to be harsh on you on this part since you stated that English was your first language. You used the wrong tense in some parts, a few typo's and words not where they're meant to be. This 

You should PUT SPACES next time~ :) it's the right way to type, we don't want it to become a habit!~~~

[Characters] 7/10

I think I gave you a pretty high score for this, it's just that the brothers are pretty similar in their personalities. I couldn't figure how they were meant to act.

And will the girl have a lover? This story probably didn't catch my eye because it didn't say if she had a lover or not :P

[Ending] ---/10

No ending~ One more thing, try not to use swearing other than when the characters talk. It doesn't look very good XP

TOTAL: 43.5/90      /100

Sorry if you're disppointed with your score :<

This is only my personal review. Don't hate me please!

Reviewer: MinaFish