Yejin has spent half of her life in and out of hospitals and the other half at home where her overprotective parents were keeping an eye on her at all times because of a heart disease. She has never had any friends outside of hospital, she was home-schooled and the only people she used to meet on regular basis, other than her parents, were her piano teacher and her doctor.

When one night Jiwon wakes up in bed with her best friend's little brother, she