Ha Ji Won is a senior at an all-girls school in Korea. She is famous for her boyish character, hate boys and a black belt holder in taekwondo. Some of the juniors were afraid of her 'fierce' look, but others were fond of her 'charm' and beauty. Because she hardly talked about boys, many thought that she preferred to 'date' girls rather than the opposite gender. But that never bothered Ha Ji Won, until a new girl arrived and started a new rumours at the school.

That girl is Song Ji Hyo, a transferred student from a mix school in US. She is very outgoing and open-minded about relationship of all kinds - be it with the opposite or of the same gender. She used to date a handsome boy named Lee Dong Wook from her previous school, but their relationship ended because she couldn't stand his 'overprotective' behaviour and never-ending jealousy. Song Ji Hyo was hoping to forget her former boyfriend and focus on her study at the new school, but he kept following her around and waited for her everyday after school hours.

To escape from Lee Dong Wook, Song Ji Hyo had to leverage on Ha Ji Won's boyish personality and convince her former boyfriend that she is 'dating' her senior. At first it was just an escape plan, but when Ha Ji Won started to 'like' her.. things began to get more complicated. Can Song Ji Hyo save herself from the love triangle? Or will she 'date' Ha Ji Won for real?