Childhood. He said that he would protect her forever and never leave her. A little while. They were far apart, and he became a diamond bachelor with a high status among the plutocrats of City A. And she was just an unknown passerby in the vast sea of people. What happened ten years ago that made him break his promise and leave her. Today, ten years later, an accident, a party, a dance, and a person reveal a past that was once deeply buried in my heart. She and him will never be able to go back to the past. Her best friend's intervention and her mother's death left her with nothing. When the truth comes to light, can he save everything and go back to the past? ? ?