Everyone knows of the Black and White Impermanences, but they do not know that there are two other kinds of Impermanence in Hell: one wearing green, and the other wearing red. They are specifically responsible for capturing fierce ghosts that have escaped from Hell to the mortal realm.

Tan Yangzi is a solitary Green Impermanence; his partner, the Red Impermanence, died three hundred years ago. However, he is accustomed to coming and going alone, so he doesn't need his superiors to assign him a new partner.

Yet, Tan Yangzi still gets a little lonely. So, ten years ago, he took in a nine-year-old boy as his disciple, teaching him martial arts in his spare time, much like raising a small animal to keep him company and relieve his boredom.

It's just that he didn't expect this disciple to grow up ten years later, spending all day thinking about becoming a man his master could rely on...