Four boys have known each other for the longest time. They are pretty close and when they go on a school vacation they all separately encounter a mysterious voice coming from one of the hotel room balcony. The boys try and figure out who the mysterious girl is.

They soon find her and have to find a way..

To win her heart.

Soon enough, all the boys encounter a beginning with her, which brings ties of friendship and love.~~~~~~~~~~~~~~~~~~~~~~~~~

Kim Kibum(also known as Key):

Key is the funny guy but it's hard to tell when he's kidding around or when he's serious.

He tends to be headstrong and has a bull-like personality sometimes.

Key is hard to read which makes it difficult for Mystery girl to connect with him when they meet.

Actually, their first encounter .

~~~~~~~~~~~~

Jung Jinwoon:

Tall, handsome and smiles a lot. He's sweet and caring, and he cares a lot for his friends and family.

He works hard in everything he does, giving a good reason for mystery girl to like him.

Their first encounter is sweet and innocent.

~~~~~~~~~~~~~~~~~~~

Mir:

Funny and cute. He seems like the youngest in the crew of four. Although he loves joking and teasing, he knows exactly when to act serious. He is very pretty-boy like and isn't afraid of acting care-free and crazy, just like mystery girl sometimes likes being.

Their first encounter is cute and fun.

~~~~~~~~~~~~~~~~~~~~~

Son Dongwoon:

Dongwoon is the most mysterious out of all the guys, hiding his thoughts and feelings behind a charming smile he has. He likes to joke around and tease too, but doesn't know how to approach it very well. He can be cold-hearted even when he doesn't want to be, giving a reason for mystery girl to warm is heart up.

Their first encounter is slightly awkward.

~~~~~~~~~~~~~~~~~~~ Mystery girl(also known as Seo Joohyun(Seohyun))

Sweet and funny. She loves to joke around and hang out with her friends. Sometimes she cries because she's sensitive but she can also make people cry. Seohyun likes reality and so she's blunt with herself and doesn't dream about so-called silly things.

She cares about a lot and is very determined.

She can adapt to whoever she hangs out and has the ability to connect with people.

She has amazing musical skills which is what makes the boys fall for her.