She is a monster wandering in the world, immortal and immortal. Because of her unique ultra-low sense of existence, it is not easy for ordinary people to see her. Only the dying people and those with deep obsessions can easily see her. She only feeds on the last breath of the dying person. Because someone was so obsessed that he couldn't bear to regret it and died, so he reached a deal and fulfilled his wish, but the world didn't know his name and called him a dream traveler. Recently, she was entrusted by a mysterious client to take care of a young boy until two years later. So, what will happen in these two years?