She used to be so trusting and dependent, thinking that he was everything, but a farce of "evaporating from the world" completely destroyed her whole world. When she was at a loss, a familiar yet unfamiliar young man suddenly broke into her life and completely changed the trajectory of her life. From being strangers to knowing each other, while laughing and scolding, the two of them became closer and closer, but the shadow of the past always made her hesitate. At this time, the man who made her unforgettable in life and death appeared again, accompanied by the so-called "fiancée". What was the reason that made him leave without saying goodbye in the first place, and why is he now a stranger when he comes back? What mysterious background does that young man who suddenly appeared have?