The innocent and kind-hearted girl Hena (Park Shin Hye) lost her father when she was very young. Her mother runs the family hot spring bath left by her father. She lives with Hena's aunt and her daughter Zhenya (Asami Reina) in a simple and peaceful life. Zhenya is smart and beautiful, but she always feels that she is not as good as others and is jealous of everyone's love for Hena. When she fell in love with the second generation of hotel tycoon Fujiwara Ryu (Uchida Chaoyang), she found that Fujiwara Ryu was in love with Hena. One day, her mother carefully told Hena that she had remarried, and the person she married was a Korean man who often went in and out of the hot spring bath. Soon, Hena had a new father and her brother Yunshu (Lee Wan), who was legally a brother. When Yunshu was ten years old, her mother died of a serious illness. Since then, Yunshu has closed his heart and refused to communicate with anyone. The unfamiliar environment made Yunshu more lonely and autistic. Hena felt his inner pain and hoped to warm Yunshu's heart with her efforts and sincerity and let the smile return to his face. Slowly, Yun-seo and He-na fell in love, but where will this forbidden love arranged by fate go?