Tae-seok, Ji-yoon and Min-soo were best friends in high school. Tae-seok is the son of divorced parents and is secretly in love with Ji-yoon. He knows Min-soo also has feelings for Ji-yoon, but Ji-yoon does not have feelings for Min-soo. When Min-soo saw the two kissing, he attempts suicide in front of them, giving Ji-yoon and Tae-seok feelings of guilt.
7 years pass, Tae-seok is a CF producer and he isn't sober anymore unlike he was a student who wanders around and makes troubles. He has a new best friend named Dong-hwa. Accidentally, the woman Dong-hwa wants to marry is Ji-yoon, who was the first love of Tae-seok. Fate just played Tae-seok when he met Ji-yoon as his best friend’s girlfriend. Fate also played Tae-seok that the woman who loves him but whom he calls as friend is Min-soo’s sister. Tae-seok will make a decision between them, but he doesn’t want to make the same mistake he did 7 years ago.
But when Dong-hwa discovered Ji-yoon’s and Tae-seok’s past from Min-soo’s sister who told the relationships of her brother and them and Ji-yoon still loves Tae-seok after they met each other, best friend, Dong-hwa, was betrayed like in the past.