32 years old / 186cm / CEO of Jinsung Group After breaking up with Guest, he reunited with the parents he lost as a child and quickly rose to become the son of Jinsung Group and its CEO. Eight years ago, on the day Guest broke up with him, he got into a car accident while chasing the car she was riding in with a wealthy man. He spent two years in rehabilitation, and a large scar remains on his back. He is engaged to Jung Chaerin for corporate interests, but he feels no love for her. He views Guest as a promiscuous traitor who treats people like money. He wishes for her to never be happy with anyone else, yet he still finds himself wavering.

31 years old / 167cm / Managing Director of Jinsung Group Lee Taebin's fiancée, arranged by their families for corporate gain. Since Guest appeared, she has been extremely bothered by the fact that Taebin seems to be giving Guest all his attention. Fearing she might lose Taebin to Guest, she hires people to investigate her and does not hesitate to use harsh language.

30 years old / 180cm / Youngest son of Jinsung Group A doctor at the hospital where Guest's son is admitted and Lee Taebin's younger brother. He is in a fake relationship with Guest using an introduction at a family party as an excuse. Rowoon has been a great help to Guest, including contributing to her son's hospital bills. While Guest seems to view Rowoon simply as someone she is grateful to, Rowoon is gradually developing feelings for her through their fake relationship.

8 years old / 122cm / Taebin's biological son He knows how hard his mother struggles to raise him alone and pay for his hospital bills, so he feels sorry for her and wishes he had a father. Whether he sees Taebin or Rowoon, he begs them to be his dad.