Skip at the night's event…
Nayoung wears a blue night gown that is off shoulder, there's three layers that shading the gown. It looks so suitable with the theme, late at night.
She lied to him and went to the event. Alone without a partner and decided to not take part on the dancefloor.
"Nayoung-ssi, where's Hyun? I thought both of you were together tonight?" her classmate asked.
"He'll not attend tonight's event, I'll just be sitting here…" she replied with a bitter smile.
"Okay, but better for you to get a partner~" she waved while walking away.
Nayoung sighed and sat in the chair, no one was having a partner or group to talk with but she's alone with a glass of cocktail in her hand.
"Seoknam also wasn't here…should I just leave?" she mumbled then, the middle of the dance floor was empty. She knew that the dance was going to start.
She decided to see the performance then leave afterwards.
The lights were off and the spotlight in the middle, lit up. There's a guy in the middle of the dancefloor and Nayoung was frowning. She takes a closer look but the guy wears a mask that covers his eyes.
He danced a tango in the middle of the dancefloor with a perfect blue suit. Is it a coincidence to have the same color as her?
He moves closer and closer to her and she takes a few steps back. But the guy stopped right in front of her. He gave away his right hand and Nayoung was confused.
"My love, can you be my dance partner tonight? We're having the same outfit's color~" he said in a very flirty and sweet voice. She hesitated to take his hand but at the end, walked in the middle of the dance floor and presented the tango.
"Be more gentle my love~ I'm not gonna eat you~" he giggled. She can feel the butterflies in her stomach but it's kinda weird because that feeling only occured when she was with Hyun.
"Are there any butterflies? Or…" he grabbed her waist near to his body then spinned her.
Her back met his chest and he slid his hand to her belly and whispered to her ear "I need to give you some?" he giggled in a very flirty but devilish way. 
He's like the devil of lust that's gonna torture you all night long and not gonna let you out from his grip. Don't even let you see the light. The real shadow that's gonna make you disappear forever from life. But there's a calm that's gonna keep her from any dangers.
"Who are you?" she finally asked.
"I'm…" he moved one step
"Your…" he spinned her around and grabbed her waist.
"Future boyfriend…" he leaned forward while she was still in his arms.
He slowly moved his face towards her and they were in their own world. The crowd gave a round of applause and cheered.
They stood at the beginning position and Nayoung was curious that she opened his mask. She was gasping as the person she danced with was Hyun. He actually attended it.
His appearance is undercut with long sides brownish hair. Is he dyeing his hair? His suit that tells the shapes of his masculine body, very forbidden to see it but everyone's eyes were on them right now. 
And his lips were so soft just now, I can't even tell whether it's jelly or lips.
A few seconds they became the spotlight and other dancers or their classmates moved to the dancefloor and they danced the waltz.
After finishing the dance, everyone gave a round of applause and the situation returned to normal.
…
Nayoung keeps drinking cocktails and sometimes wine. The nervousness that she felt was surrounding her. He stands right next to her and talks with his other friends. It was a few minutes after that performance ended and they still didn't have any talk yet.
Shortly, Hyun take Nayoung's glass.
"How much are you gonna drink? You'll get drunk…" he put the glass away.
Honestly, Nayoung doesn't feel drunk at all. Either she got a good consistency or she was just too nervous. 
"I'm not yet drunk…" she said. He can see the blush redden on her cheek, the effect of the wine plus her shyness.
"Glad to hear that…I want to talk with you about something…" he said.
"What is it?"
"Follow me…" he commanded while holding her wrist.
"Where?" she slowly pulled her hand.
"Outside of the ballroom, let's have our own moment for a while…" he said and continued walking while she just tailed from behind.
Once they stand outside of the hall, Hyun holds both of her hands "you look so angelic tonight~" he smiled.
"Thank you, you also look so stunning tonight." shyly she told him.
Suddenly, he took out something from his pocket and put it on her finger. It was a ring with a beautiful color around it. On top of it, there's her full name.
"It's a gorgeous ring!~" she touched it excitedly and was fascinated by it.
"It's an angel stone, arval~ suitable for you~" he said.
"Thank you very much~ I appreciated it~" she hugged him tightly.
"But…" she let go of him.
"Why did you give me this so suddenly? You said that you'll not attend the event because something is coming up?" she looked at him, tilting her head a bit.
"Yeah, something comes up…but I didn't say that I will cancel our dance~ I just don't like the event…" he chuckled and she hit him.
"You're a liar!!! Keep lying to me!" she hit his shoulder.
"No! I didn't lie! I just said that I'll not join the event, not dancing with you all night long~" he pinched her cheeks. It's so fluffy, not gonna lie about it.
"I hate you!" she pouted in anger.
"Don't worry, I'll love you~" he patted her head.
"Don't play games with me! I know your tricks!" she pointed right in front of his face.
"Then you should know how big my love for you is that I can't hold myself to not looking at you~ we're friends but I can't deny that my feelings for you were actually more than friends…" he confessed.
"Since when?"
"Since the moment when you're annoyed me in front of the door~" he said and she's been shy.
"The heck you fell in love so fast! If it wasn't me, then you must have fallen in love with someone else!!" she was pissed off and facing away from him.
"No, that's not…if you're not the one who's gonna knock, maybe there'll be no one cause you're the one who dared to annoy me like that~!" he laughed out loud.
"Ne! I'm an annoying girl with troublesome behavior, I don't deserve to have any friends if I don't annoy them!!" she is still mad at him.
"No, I'm just kidding~ don't be too mad…if it's not you who knock, there'll be no other people because destiny wants to show us something and it's feeling…how two—" he stopped, almost saying two creatures that's gonna make her confused.
"Two what?" she asked.
"Two different people from different worlds meet and never even know that each other exists…" he said.
"Hyun-ssi…when will I hear about your origin? The fiend that flies down to the earth…when will I hear about the truth about your black wings?" she continued and it made him totally shocked.
"How…" Hyun widened his eyes, terrified in his eyes.
"I know since the moment you let me into your house, there's one room that tells me everything about it…" she admitted.
Flashback On
"Come in…" Hyun invited her in.
"Why do we need to do work in your house?" she asked.
"Cause I'm the one who wants it…" he sat on the couch.
"Ouh…then, how are we gonna start?" she sat down.
"Are you dumb or something knock your head? Just do it just how you do it!" he frowned.
"Okay…no need to be mad!" she was pissed off.
Both of them help each other with the earlier assignment that their lecturer gave.
"This is tiring…" Nayoung mumbled.
"It's just a few assignments, don't be so picky…" he said without looking.
"Your body and my body were different!" she grumbled.
"Yeah, I got more stamina than you…" he teased.
"I'm gonna get some water…" she was about to stand  up but he hold her shoulder.
"Let me do it…" he volunteered.
"Thank you…" she replied.
Hyun was making them drink and Nayoung was zoning out when she heard someone is calling her name in whispered.
"Nayoung-ssi…" it becomes clear in her ears.
She was looking around but there's no one except her and Hyun. She called his name but he didn't respond. Nayoung finally walked towards the person that called her name.
She can't control her body as it feels like they're a string that wrapped all over her body and pulled her to one way.
At the end, she stopped in front of one room. At first, she didn't even feel any curiosity to open it but the curiosity became bigger and bigger until it became a desire to look at what's in the room.
She opened the door and entered it, there's a few pictures on the wall and a strong smell of blood. She feels nauseous and wants to throw out but then, the door won't open.
Nayoung was so scared that she hit the door many times and there's one energy that absorbed every strength that she got.
Nayoung dropped down and leaned at the door, one black smoky thing came towards her. 
"He's…a…demon…stay…AWAY!!!" it screams but Nayoung has no strength left to move so she just feels the shivers down her spine.
For an instant, someone pulled her out from the door. It's Hyun that pulled her into his hug. Both of them laid on the floor with her on his chest.
"For real…I forgot to lock the door…" he mumbled but she heard it. 
Her sightseeing was blurry and blank. She fainted on his body. 
…
"How can a human like you survive in that room? I thought you're gonna die right after getting in…" he said after putting her on the couch. Looking at her white pale and chubby face. Her pinkish lips are shiny. 
"I shouldn't bring her in…" he sighed and just continued doing the assignments.
…
"Ugh…what…what happened?" Nayoung opened her eyes and sat on the couch.
Hyun handed her a cup of warm water and she drank it.
"You're fainted…" he said shortly.
"Me? Why? Why I—" Nayoung then remembered everything clearly and speechless, what she saw in her dream wasn't actually a dream. 
"Why you what?" he asked.
"No…I just have a headache, I want to go home…see you at college tomorrow…" she said and immediately packing up her things then rapidly walked out terrified.
It feels like in a horror film and she can't believe what she sees, Hyun in a demon form. Not the real him but she can see the reason why he's on earth.
"There'll be no way he was a demon…a real demon…" she said while his face was still playing in her mind.
Flashback Off
"Yes, I was a real demon and I'm just studying on the earth because I refused to get into the academy and help my appa at the torturement palace…" he admitted and she just smiled.
"Why are you smiling?" he asked in a weird way.
"I'm happy to see that you can tell the truth, hope you'll not lie again~" she smiles and it shoots into his heart.