Two similar teenagers ( she an he) have been bestfriend for a couple of years. They hang out together almost everyday and do the same thing everyday because they had a dream to become a star but what would happened when one of them debuted first, when their manager said that they will separate for a while.  Then, 5 years later Donghae became famous and was in the group called Super Junior with 13 memebers. And, when Yoona thought her time of becoming a famous star was a waste of her youthful time, her manager called her to go to his office and told her she was debuting with a group called Girls Generation's ( SNSD). What will happened?? Donghae haven't seen Yoona for almost 2 years because they lost contact with each other when Dongahe was promoting their songs and he was so busy that he forgot his bestfriend all of a  sudden. He realised that he forgotten all about Yoona and promise himself that he will make it up for her. But what he doesn't realised is Yoona is not the same Yoona dongsaeng he knew before.

Im Yoona the face of SNSD is  shy, friendly, kind, loveable, and loves to make everyone happy. But she will never forget how his ex-bestfriend treated her. She wanted to get a revenge on him

Donghae from the group of SUJU is a good dancer and has the ability to sing. he wants to make everything right from his bestfriend Yoona.

Taecyeon- he won't be in the story until Yoona would debute from the group.