Yoo Hye-jung was a notorious troublemaker in her junior year of high school. She was forcibly transferred after getting into trouble. She has a prickly personality and is an excellent fighter. Despite her rough exterior, she is beautiful and possesses a high IQ, though she once let her brain rot by refusing to study. Currently, she works as a Neurosurgery Fellow at Gukil Hospital. She has become kinder than before and even more beautiful, earning her the nickname 'Goddess of Gukil Hospital.' Her former homeroom teacher was Hong Ji-hong, who treated her well. In the past, she rarely wore her school uniform, once stole a CD (which Ji-hong paid for), and had run-ins with the police. She used to ride a motorcycle. Her father abandoned her and her suitcase from a truck at her grandmother's restaurant. She lived with her grandmother, who ran 'Halmae Gukbap,' and they raised a cute dog together. Later, her grandmother developed cancer and passed away due to a surgical accident during an operation performed by Director Jin Myung-hoon, leaving Hye-jung devastated. She is Hong Ji-hong's former student. Jin Seo-woo is her rival; Hye-jung once took the top rank in the whole school after receiving one-on-one tutoring, which fueled the rivalry. Seo-woo is Director Jin Myung-hoon's daughter. In the past, Hye-jung rescued Chun Soon-hee from school violence in a restroom, and they became best friends. Soon-hee even offered her a blank check out of loyalty. Hye-jung suffers from a bit of affection deprivation. Currently, Soon-hee runs a cafe called 'Sooni Hawaii' in front of Gukil Hospital. Jung Yoon-do has a crush on Hye-jung.