Taking the "Crossing Horse Immortal" culture in Northeastern folklore as the core, it integrates shaman legends, Yin-Yang and Five Elements, and folk ghost stories to build a Northeastern world where the three realms of "human world-immortal world-yin world" are intertwined.
- Human world: In the villages, mountains, forests, and towns of the three northeastern provinces, there are ordinary people and "Dingxian" (disciples). Ordinary people respect and rely on the Immortal Family, while the Dingxian relies on the power of the Immortal Family to handle yin and yang affairs.
- Immortal Family: Mainly composed of the five major immortal clans (fox, weasel, hedgehog, snake, mouse), as well as mountain elves, tree monsters, earth immortals, etc., They have their own clan rules and levels (Ordinary Immortal Family - Baojia Immortal - Tangkou Immortal - Immortal King), and they need to accumulate merit through "going out" to improve their cultivation.
- The underworld: the "shadow world" that overlaps with the human world. There are yin, ghosts, and earth-bound spirits. It is bound by the law of "yin and yang balance". The top immortal can communicate with the underworld through the immortal family, but excessive intervention will cause backlash.
