A lonely and helpless girl fell in love with a melancholy boy, only to find out that he was a down-and-out vampire noble. In order to help him survive, she worked hard to make money and secretly bought blood for him. The meticulous care brought the two closer, but the girl who thought she had gained love found out that he was just using her. From suspicion to confirmation, the girl finally left frustrated. But the young man gradually realized how indispensable she was, and tried hard to save her again and again, but the soft-hearted girl still stayed. For her, the boy wanted to become a human. After going through all kinds of hardships, the boy finally turned into a human being, but the woman who made him want to be an adult was long gone. It turns out that once you pass by, you really can't go back.