Oh Yeon-joo : Starring Han Hyo-joo

Working as a resident at a general hospital, Yeon-joo suffers from a lack of sleep and has no time for relationships. She wants to be a brilliant doctor, but her personal life is a mess as she cannot find a stable relationship with guys. Even though she is quite lovely, she finds herself being used by guys and eventually breaking up with them. Then one day, she encounters the man of her dreams, and it was obvious that he was going to ruin her life.

Kang Chul : Starring Lee Jong-suk

He is a younger entrepreneur who owns a broadcasting network called, “W” with a personal net worth of $800 million. Not only is he blessed with genius-level of intelligence and good looks, but he also has a humorous personality and gentle manner. One day, a mysterious woman saves his life and then vanishes into thin air. He instinctively knew that she has answers for all his curiosity. But all he knew about her was her name, occupation, and a phony number that is written on her business card. In fact, it does not even exist in the world he lives in.

Oh Sung-moo : Starring Kim Ui-seong

He is the father of Yeon-joo and a famous comic strip artist. As a long-suffering artist, he stuck-up with a big ego after he has found sudden fame. Also, he has an inferiority complex that made him deal with lots of pent-up issues. After a sudden poverty, he faced of divorce with his wife. He is a sensitive, moody fellow who also finds it stressful drawing a long-running comic strip. He is irritable and a functioning alcoholic. He holds the key to everything that is consuming Kang Chul’s and Yeon-joo’s lives.

Yoon So-hee : Starring Jung Yoo-jin

She is an excellent secretary working for Kang Chul, and she immediately catches what he thinks. She has a chic style with a volatile temper. Despite being a secretary, she nags her boss, Kang Chul and speaks her mind. Although she is sexy and sassy, she has had a long crush on Kang Chul since she was in high school. When Oh Yeon-joo suddenly appears in Kang Chul’s life and shakes things up, she finds her as a threat to her relationship with Kang Chul.

Seo Do-yoon : Starring Lee Tae-hwan

He was once the best mixed martial artist in Korea. He is a confident guy with, loyal manner. When Kang Chul tried to recruit him, he decided to quit mixed martial arts without any hesitation and joined him as a business partner. They became a closer business partner showing powerful chemistry. He feels pressure to see Soo-hee nursing a crush on Kang Chul.