If this life is like a book, it is divided into three parts: upper, middle and lower. So in the first part, the elder sister and the younger sister are very happy. The elder sister loves and protects her younger sister. The younger sister loves and is considerate of her younger sister. If there hadn't been any misfortune from the central part of the country, maybe they would have lived happily. Unfortunately, a sudden disaster in the middle of the country caused the confused and lovely sister to grow into an iceberg. The only thing that can make that iceberg melt is the sister who writes the death certificate. God just likes to play tricks on people, since the second part allows the two sisters to meet. So, how to proceed with the lower part?