The story starts with Yoo Jeongyeon. A city girl who is a rebel that has to get everything she needs and all that she wants. No one can stop her. She lives only with her mother in a big mansion because of her separated parents. She actually has an older sister but her sister lives with her father. She always messes around, doing crazy stuff but her all time favorite is drag racing. Which is illegal.

Due to her constant misbehavior, her father forced her to join their medical mission and this is where she'll meet Hirai Momo.