Main Characters:

Kim Hyo In

She is a smart but happy-go-lucky girl. She wears glasses and sometimes she is called " Pretty Glasses" because of her looks and intelligence, She likes her childhood friend, Youngmin but suddenly develops feelings for Kwangmin.

Kim Hyo Eun

She is the younger twin of Hyo In. She is more popular than Hyo In for she is prettier and doesn't wear any glasses.  She likes Kwangmin and even asked her twin to set a date for them.

Jo Kwangmin

He is popular in their school. Kwangmin is the silent and cold type but when he is with Hyo In, he changes.

Jo Youngmin

He is also popular like Kwangmin. He likes Hyo In but he can't tell her for he knows that his brother likes her.

Not so Main Characters:

Kim JongHyun

Older brother of Hyo In and Hyo Eun. 

Lee Taemin

A total nerd who was saved by Hyo In from bullies. Develops feelings for Hyo In.