Cassie is a 17 year old girl who leaves with her best friend,Song Jihyo. They are roomates. Cassie's parents passed away when she was 10. The Song family were the only one who knew about Cassie's personal background. Cassie and Jihyo will always hang out together in school since they don't want to be involved in the dramas.Kim Eunmi always bullies Cassie when Jihyo is not around to protect her.

One day,12 kpop idols transferred to Cassie's School. Cassie did not care at all. The idols were from a kpop boy band Exo. When Chanyeol saw Cassie,he liked her. A lot.