Xia He is originally an ordinary working-class person. To ease her living burdens, she takes a job at a midnight milk tea shop on a mountaintop, unexpectedly discovering that the front door connects to the ancient martial arts realm and the back door connects to the demon court. With various everyday milk teas and market snacks, she exchanges with visitors from both realms for rare spiritual objects, carrying out cross-domain trade in a small mountain shop, gradually accumulating a bountiful fortune, and unintentionally promoting peaceful coexistence between the two realms, becoming a presence mutually respected by both realms.