The story takes place in the modern, bustling metropolis of Binjiang City. On the surface, it is no different from any other major city, with towering skyscrapers and streams of traffic. Yet beneath the night sky and urban legends, an ancient system known as the Underworld Bureau is gradually losing control of the realms of the living and the dead for reasons unknown. As its rules weaken, more and more spirits linger in the world, and strange creatures begin to multiply. The Yin-Yang Delivery System that protagonist Zhou Mo accidentally binds to is one of the backdoor programs left behind in ancient times, designed to mend the rifts between the two realms and maintain basic order. The System settles karmic debts by delivering takeout infused with “yin virtue” or “yang energy” to specific underworld customers, such as ghost officials, underworld deities, and unusual spirits. Its rewards might include an extended lifespan, a minor supernatural ability, or real-world currency. What seems like a simple delivery job is, in truth, a path that treads the line between life and death at every turn.
