Park Gyuri = The heiress of Park company, loves to fool around, careless, and spoiled child in her family. She actually study abroad but her father forced her to come to Korea to take care of their company. She also appointed to be Kang Jiyoung's fiance. She try her best to reject her father last option, to marry Jiyoung. She finally give up when her father tell her that she have bad records when she's study abroad, if she want to continue her study then she need to marry Jiyoung or else she won't be permitted  to go outside Korea. She's 24 years old.

Kang Jiyoung = A daughter of Kang's corp, she's smart and a bit hard to approach. When her father said that she should marry Park Gyuri although she's unwillingly accept it but she doesn't even refuse it. She's also appointed to be Gyuri's  personal secretary to make Gyuri learn about stuffs at work. She's 18 years old but she already graduated from MIT.

Hara, Seungyeon, and Nicole = they're all Gyuri's ex but the three of them are still good with Gyuri and moreover they are best friends. They will help Gyuri's plan to stop Gyuri's marriage.