Modern cities are not "places without martial arts", but hidden "urban spiritual veins" that run through the underground - a special energy network formed by ancient practitioners who used mountains and rivers as the basis to bind the core of cultivation to human settlements. While the spiritual vein nourishes the city, it also breeds "aura" (the energy required for cultivation). However, in the past hundred years, the spiritual vein has become "turbid" and breeds "turbid shadows" (monsters formed by aura pollution, which look like distorted city silhouettes, such as "street lamp shadows" and "building shadows"), and will attack people who perceive the spiritual veins.
