First Impressions:

Okay so let me just start off by saying that I have never read a zombie-based story. But in my honest opinion, I find the whole idea of zombies...bleh. I don't actually know how to describe it so I'll use the word 'bleh'. So when I saw that your story was a zombie-based one, I kind of cringed. But hey, this is only a first impression and first impressions change ;)

Title:

RISE of the UNDEAD. I wouldn't say that's one of the best titles to come up with though it does summarise your story plot. Even so, I've searched for stories with the same title as yours and I found none so props to you for that :) The title seems like a common one though it isn't. I'm not asking you to change the title of your story but in the future, should you come up with a title for your new story, I advise you to give it more thought. Pick a title which would stand out from others. For example, I have come up with a few alternative titles for your story.

1. 'It'  

Why 'it'? Well it all depends on how you look at it. 'It' can be short for 'I'm it'; which in a way refers to Sonnie being the one everyone has chosen to rely on. Or it could refer to the zombie. Also, when readers see this title, they would start asking questions. 'What does 'It' refer to?' 'Why 'It'?' 'What do you mean by 'It'?" 

2. Dead Rising

Why 'Dead Rising'? To be honest, I had found that title on your first chapter and found it to be a good title. xD It gives off a mysterious feel and though the idea of it is almost similar to 'Rise of the Undead', it doesn't give off that 'cliche title' feel. This title would make readers stop and think for a second. "Is this some sort of zombie attack?"

3. Surviving 

Why 'Surviving'? In a way, it refers to the whole idea of surving the undead. Also, it gets readers thinking, "Surviving what?" 

And those are the examples I have :)  If you have noticed, these three titles have 2 things in common. Firstly, the titles are the most, two words long. And secondly, the titles get readers thinking. Choose titles that would make readers stop scrolling as well as titles that would leave readers with a question mark. It'd make them more curious about your story :)

Description & Foreword:

I have to be honest here. Your description was disappointing and it could be better. Indeed, the description is supposed to be a summary of your plot but the way you phrased your sentence had no feel. I want to be able to read a description and become even more curious with every sentence I read. 

This is your description:

'A disease break-out has swept across Seoul and is spreading rapidly. Scores of the undead haven't been able to rest in peace and continue to pound on the doors of the living. So far, for the past week, Sonnie Kay, aka Na Somi, was able to save majority of the members in SM Entertainment. However, everyone is depending on Sonnie for survival. Is she able to take this challenge?'

This is the one I've come up with:

'With a disease break-out on the loose, Sonnie Kay a.k.a Na Somi must protect the remaining members in SM Entertainment. Everyone is depending on her for surv