an agreement that was made long before, shortly after they were born, was made by their ancestors to strengthen their friendship bonds. they know about the agreement and absolutely object it,they never met before and their family had lost conection towards each other after their grandparents died. Taecyeon's parents, MR.OK and Madam OK try to fulfill their parents wish by tying the knot between their son and their parent's bestfriend's grandaughter. will they suceed? 

main characters:

IM YOONA

she knows about the agreement and lost her parent in a car crashed when she was in high school. a strong and independent  woman, she live with her friends Yuri,Sooyoung,Jessica and Seohyun. she's very pretty and lots of boys in her university likes her but she's not intrested on them. she's very demure after the accident.

OK TAECYEON

he is the son (an heir) of the owner of the richest company in South Korea (according to Forbes).he is well educated and good in business. he is known as a playboy and has no manners. but he is a workaholic just like his father,he barely spend time at home, the office and the night club are  his favourite place. know about the agreement but object it and never cares about it.

OK TIFFANY

she is taecyeon's younger sister, very caring and protective.she was well educated in the overseas like her brother. she's in charge in family's affairs and very concerned about family's pride.she knows about the agreement and she loves yoona very much, she is one of the people who accepted yoona in the family.

JESSICA,YURI,SOOYOUNG AND SEOHYUN

yoona's housemate,go the same university as yoona. took care of yoona like her parents did and they are the shoulders that yoona cried on.

2PM

they all came from well and rich family. taecyeon's bestfriend and his bestmate for partying. they all involve in family business.

minor:

MR AND MRS OK

very well known people in South Korea. very workaholic and barely spend their time in South Korea. in the progress to fulfill their promise to their father to marry taecyeon by the time his is 23 with yoona, their father's bestfriend's granddaughter. loves yoona as they love their own daughter.