One is a terminally ill flower girl, and the other is the messenger of the God of Death. Originally, the relationship was just "mission" and "performing tasks", but due to various changes in the contact process, choice and dedication have become the link between the two of them in this special "friendship", and it is also the theme that the author wants to express.
Intention: No matter how hateful the devil is, he may be an angel. No matter how painful things are, we must face them with a smile. No miracle happens for no reason.