Gang Suil (cast. Choi Sujong)
His real name is Kim Yeonghun, and he is the biological father of Doran. Immediately after he was born, he was abandoned in front of an orphanage, so he doesn't know who his parents are. He has been a warmhearted guy since he was little. He took care of Dongcheol, who was abandoned just like him, as if he were his little brother. He was accused of a crime that Dongcheol had committed and was sent to a juvenile detention center. Life was not kind to him after that. He still managed to meet a loving wife, and they had a beautiful daughter. He worked hard for his family. His daughter was the new apple of his eye. But the happy days did not last long. His wife was taken with acute heart disease. While trying to earn money for her surgery, he inadvertantly committed a crime and ended up in jail. After 27 years, he gets out of prison, changes his name, and starts a new life. He hopes that no one would recognize him, especially his daughter Doran.