changed after meeting teacher Hong Ji-hong, who helped her find her goal in life. Yoon Kyun-sang as Jung Yoon-do Jung Yoon-do is a neurosurgeon as well as a visiting staff who is from a wealthy family. He is not good with rough situations in society. However, he knows how to handle his work with strictness. He finds himself attracted to Yoo Hye-jung, who is very different from him. Lee Sung-kyung as Jin Seo-woo Jin Seo-woo is a neurosurgeon and also friends-turned-enemies with Yoo Hye-jung. She liked Hong Ji-Hong, but seeing the growing relationship between Hong Ji-hong and Yoo Hye-jung, she causes trouble for them. This in turn caused them to part ways. Forgetting about Hong, she starts liking Jung Yoon-do but again feels inferior to Hye Jung due to Yoon-do's attraction towards Hye-jung. Eventually, she reconciled with Hye-jung and restored their friendship. Additionally, in the end, she fell for Young-gook and became his girlfriend. Supporting People around Hong Ji-hong Lee Ho-jae as Hong Doo-sik – Ji-hong's adoptive father and Gookil Hospital's chairman Yoo Da-in as Jo In-joo – General Surgery's specialist People around Yoo Hye-jung Kim Young-ae as Kang Mal-soon (cameo) – Hye-jung's grandmother Jung Hae-kyun as Yoo Min-ho – Hye-jung and Yoo-na's natural father Park Ji-a as Lee Ga-jin – Hye-jung's stepmother and Yoo-na's mother Han Bo-bae as Yoo Yoo-na – Hye-jung's younger half-sister Ji Soo as Kim Soo-cheol (Guest: Ep. 1, 2, 3, 5, 7–8) – Hye-jung's friend Moon Ji-in as Cheon Soon-hee – Hye-jung's best friend and Seo-woo friend. People around Jin Seo-woo as Jin Sung-jong – Seo-woo's grandfather and Gookil Hospital's vice president Um Hyo-sup as Jin Myung-hoon – Seo-woo's father and Gookil Hospital's director Yoon Hae-young as Yoon Ji-young – Seo-woo's mother People of Gookil Hospital Jang Hyun-sung as Kim Tae-ho – Gookil Hospital's deputy director and Head of Neurosurgery as Kang Kyung-joon – Neurosurgery's 4th year resident doctor Baek Sung-hyun as Pi Young-gook – Neurosurgery's 3rd year resident doctor and Seo-woo's friend who had a long-time crush on Seo-woo herself Jo Hyun-sik as Ahn Joong-dae – Neurosurgery's 2nd year resident doctor Kim Min-seok as Choi Kang-soo – Neurosurgery's 1st year resident doctor as Baek Ho-min – Head of General Surgery and Hospital's public relations chief Lee Seon-ho as Jung Pa-ran – General Surgery's teacher, Ji-hong's friend and Yoon-do's uncle Choi Sung-jae as Hwangbo Tae-yang – General Surgery's 1st year resident doctor Pyo Ye-jin as