Koi is a ten year old young divine doctor who is favored by eight masters, especially with the personality of Master Xiaoba. Due to the astonishing amount of food, the masters were in financial difficulties. Xiao Ba brought koi and went down the mountain to worship Gu Yanli, a kind-hearted man from Yuncheng, as his father to relieve their difficulties. However, the koi fish mistakenly identified the world's number one demon, Li Tingchen, as their father. Li Tingchen initially rejected it, but was later moved by the detoxifying kindness and protective feelings of koi fish. Koi was harmed by the puppet technique of the Li family. Li Tingchen sought treatment from Xiao Ba and searched for medicinal herbs together. At the auction, the two unexpectedly bought Yuan Dynasty green pine stones. Koi and Xiaoba were hired by the public under the name of Kunlun Mountain Little Medical Immortal. Xiao Ba and Li Tingchen had a flirtatious dream, with the assistance of their grandmother. Later, they discovered that they had already had a connection, with koi possibly being their son