In this colorful world, there are all kinds of people, and they are all running and struggling for life. However, at some point, some creatures that should not have appeared among this group of ordinary humans, and their code name in this world is "Xiao San". They are parasites and are the ones who disrupt your normal life. The culprit is that time is advancing, time has washed away the traces of history, and the growth of the "Mistress" family has slowly threatened the peace of the world. When you fell from the heights of the clouds to poverty, the "Mistress" disappeared, and in exchange for a "contract" from the God of Death, you have been selected as the next generation of "Mistress"