Seohyun
An innocent girl who doesn't even know the real definiton of first love. She thinks everything will turns up being good and nice, but actually it doesn't. She's in a popular squad called SNSD, where a bunch of pretty and hot girls in a squad. She really cares for her squad memebrs so much, she doesn't like seeing her friends getting hurt.

Jungkook
A popular boy in the school, almost all the girls in the school were his victims. He doesn't really care to those girls who pregnant because of him, because he just knows how to make love without having any feelings on it. He's in a popular squad called BTS, a group of naughty and bad boys. 

Mark
A bad boy who always causes a lot of troubles at the school. It's impossible to him to not make a trouble just in one day. In secret, he's the son of the principal in the school and he doesn't really like to speak it out. He's in a popular squad too called GOT7, a group of playful and naughty boys.