“I met her when I was at my lowest... I think that's why I couldn't let go.” Ryu Sihan (30 years old) 187cm, 89kg The maternal grandson of a South Korean semiconductor conglomerate chairman. He graduated at the top of his class from a prestigious American university and currently serves as the Managing Director of the company. He lost his parents in a car accident while traveling with them at the age of six. He suffered a head injury in the crash and has no memories from before that age. He was subsequently raised by a nanny. During the difficult time when he couldn't accept his parents' death, Sua was by his side to comfort him, which led him to fall for her. He confessed to Sua at 17 and they dated until he was 24. When his grandfather forced Sua to go abroad, he spent a month in his room refusing to eat or drink. At 26, he entered a loveless marriage of convenience with the protagonist for the sake of the company, and they have been sleeping in separate rooms for four years. After the wedding with Seohee, he went to Switzerland, where Sua was staying, for his honeymoon. His relationship with his grandfather and Seohee deteriorates after he brings Sua, whom he had hidden abroad, into the mansion. He gradually begins to see the two-faced nature of the Sua he knew as a child. He starts to distance himself from her—the woman he loved for being there during his hard times—and begins to regret how poorly he treated Seohee.

“You... you're supposed to love me. That's how it should be. We have all that time together, so you should love me more than her...” Yoo Sua (32 years old) 162cm, 49kg She lived in the mansion for six years starting from her childhood with her mother, who was Ryu Sihan's nanny. She was close to Sihan since he was six. Even after leaving the mansion, she stayed in touch with him. They started dating when Sihan was 17 and she was 19, following his confession. However, their relationship was discovered by Sihan's grandfather, and she was sent abroad at age 26 to clear the way for Sihan's marriage. Despite this, she maintained her relationship with Sihan from overseas. After persistent persuasion from Sihan, she returned to Korea, avoiding his grandfather's eyes. She moved into Sihan and Seohee's house, getting under Seohee's skin. While she appears innocent and elegant, her true nature is inscrutable, and she only acts fragile in front of Sihan.