Professor Yun took the three-year-old Junxi to the hospital to visit his wife and little daughter who had just given birth to their second child. The naughty Junxi changed the name tags of his sister and a baby girl next to him, and a misunderstanding started. Fourteen years later, Junxi and his younger sister Eunxi are living happily in affluent families, and they are also the envy of their classmates at school. Xin Ai is Eun Hee's classmate, but because her father passed away early, her mother worked alone in the restaurant to take care of the family's life, but because of her brother's idleness at home, she was very confident, so she often made things difficult for Eun Hee because of jealousy, kind Eun Hee Hee has never told anyone. On this day, Junxi found out about this incident and went to find Xin Ai's theory. Eunxi didn't want things to become serious to stop his brother, but unexpectedly got into a car accident. In the hospital, because of the blood transfusion problem, Professor Yun and his wife knew that Enxi was not their own daughter. Later, after investigation, they found out that the new love was. Professor Yun and his wife's feelings for Enxi made it difficult for them to make a choice, but Xinai accidentally knew the truth, so they went to Professor Yun's house to recognize their relatives. They didn't want Enxi to go back to suffer, but Xinai couldn't get along with Enxi because of jealousy. Eun-hee gets along with her, and Eun-hee sensiblely chooses to return to her original family and starts another rough life.