Park Shin Hye - A normal highschool girl who doesn't like to talk to anyone. She is quiet and smart. But she is good friends with Lee Min Young.

Lee Min Young - Best friend of Park Shin Hye. She is really energetic and she gets scared fast. She always tells jokes that makes people laugh. But despite of her cheerfulness, she is also sad. Her mother has cancer. She takes care of her mother because her older brother, Lee Hong Ki, went missing many years ago. 

Lee Hong Ki - Older brother of Lee Min Young. His dream is to become a famous singer. He went missing because he got separated from them when they were escaping the fire at their home. Their father died from the fire. Min, him and her mother was running away when he fell on a cliff and landed on water. Min and their mother stopped running and tried to catch Hong ki but he fell. They thought he was dead but someone rescued him and it was Jung Yong Hwa.

Jung Yong Hwa - The one who rescued Lee Hong Ki. He saw Hong Ki floating on the water. He rescues him and lets him live in their house. He also have feelings for Shin Hye.

Park Min Young - A tough girl. She is the student council president of their school. She is also good at Martial Arts. But she is very kind and thoughtful. She is always concern of everyone.

Park Bom - An innocent girl with angelic looks. She is very shy and she spends time in the library reading books. She also loves  listening to music.

Kim Sung Je - A playboy. His looks always catches a girl's heart also his voice. But he is really kind especially when it comes to Min. He loves to dance and sing. 

Choi Min Hwan - A cute guy who acts like a little kid. Everybody loves him because of his cheerful attitude. He always acts cute which make girls faint. He is really energetic and kind. He is like the maknae of the class.

Sung Joong Ki - He acts like the older brother of their class. He treats everyone fairly and he is also a gentleman. But once you get to know him, he always teases you. He always run around like he is always happy.

Kim Ki Bum - He is a cute guy. When you see him you feel like you can trust him. And that is true. He loves to help people and he loves listening to music. He has hidden feelings for Min.

Oh Won Bin - Acts like a brother of Min and Ki Bum. He loves to play the guitar and sing. 

Kang Min Kyung - She is a bit boyish but she has really feminine looks. She acts tough but she is very shy. 

Suzy Bae - Close friend of Min. She doesn't like hanging out with boys. She always hangs out with Min and Jiyeon.

Park Jiyeon - She always fools around. She loves to eat at the cafeteria with her friends Suzy and Min. 

Lee Jin Ki - A clumsy and shy guy. Even though he is a bit older he acts like he's the youngest. He looks innocent and he always  drops something.

Lee Jung Hwan - The class joker. He loves to tell jokes that makes people laugh like Min. He always has a smile on his face that doesn't fade away.

From left to right:

Park Shin Hye, Lee Min Young (Min) , Choi Min Hwan, Kim Ki Bum (SuJu), Oh Won Bin, Park Bom, Lee Hong Ki, Suzy Bae, Lee Jung Hwan (Sandeul) , Kang Min Kyung, Song Joong Ki, Park Jiyeon, Park Min Young, Kim Sung Je, Jung Yong Hwa and Lee Jin Ki (Onew)