Title:
The title is a little too long in my opinion, it's a definite mouthful. As for the originality and creativity/eye-catching aspect - it's on the lower side due to the fact that the title is lacking something unique. I've seen stories with this title before and with titles like these, it's semi-predictable. I think the title's main flaw is the length - I think longer titles can give too much away or make readers look the other way unless it's a pretty damn catchy title which is hard to do.

Description/Foreword:
When it comes down to it, the title is smack dab in the middle of the first sentence which is good because it relates/connects to the story and the phrase 'I'll always be with you' does have several meanings which makes you wonder which meaning it holds.

Though, instead of "no matter what happen to you", it should be "no matter what happens to you" since the happen just has to have an s on it. English isn't your first language I know that and plus, it's not that big of a deal - just figured I'd point it out for you.

Another thing is "if you want a runaway", I think what you meant is "if you want to run away" because runaway describes a person. So a "runaway" is a person while "run away" is to run away from home for example, which is what I think you were aiming for.

Plot:
While reading, I got the feeling that she wasn't real or that he was suffering from some kind of mental illness or problem due to the traumatic experience he had as a child with his sister dying. The reason I think that is because the girl comes out of no where and said that she's always watching him. It's like she is his inner thoughts or guardian angel. Or maybe she's a hallucination. 

One thing I don't get is why people die around him, is it bad omen or is he just really in the wrong place at the wrong time? It's almost amazing how people continuously die around him.

Okay so I finished reading and I don't know why I was expecting something else since the tag literally said soulmateau - see? I'm slow. I get that she's his soulmate and vise versa but because soulmate stuff is usually very cliche - I won't say the plot is the most original out there because it's not.

Writing Style/Flow:
You know, I saw this funny post once. Here, I found it:

I was reading your first paragraph and when you said "to prevent the slightest penetration of sunlight from the outside" I was like 'damn.' because that's pretty descriptive. There were a few things, like in the description where an S was forgotten, that I noticed like "flashback to 5 years old Min Ki" I would personally say "five year old Min Ki" since no one is saying "I'm five years old" because then that would require an S, if that makes some sense. But besides those few things, there wasn't many grammatical errors. 

As for flow, everything flowed pretty nicely and I think I got the message you were trying to get out. Maybe not though since I am pretty slow.

Characterization:
When it comes to characterization, I think Minki's got some serious bad damn luck. If people keep dying around him, then obviously there's something - like a bad omen - just lingering around because geez, he's lie walking death. Anyways, overall he's a decent character. 

The girl isn't bad either (I always have trouble remembering people's OC names so I just call it a girl or something), she's his soulmate and she wants to help him through the traumatic events and so on. She's also a decent character.

Personal Enjoyment:
This isn't something I'd personally read but as I said before, I did take a look at it prior to this being requested; never read it but I did see it and looked at the front page. I usually don't read soulmate au's/ocxidol fanfics so I wouldn't have read it voluntarily. The only time I read a soulmate au if it's for the one ship I read anything for - which there's only one ship like that so it's hard to do that. It wasn't bad overall and it did get me thinking.