Do Hyesung was once an SM Entertainment trainee (2005 - 2009), but she left shortly after when she was 16 to pursue other future career options. Her father was the CEO of KBS World and also a close friend of Lee Sooman. Right before she left she had encouraged her favourite same-aged cousin, Do Kyungsoo to audition for SM because of his good vocals and acting skills. Her cousin had successfully entered and debuted in SM newest and currently most popular boy band, EXO.

In 2015, she returned to Korea as an exchange student at Korea University. She met up with her cousin and a few of the EXO members whom she was once good friends with until she left. They had lost contacts for several years after. However, things got more complicated than she had expected when two EXO members fell for her, one as a lover and one as a friend with benefits...