The snake demon Li Ran went down the mountain for the first time when he was 1,500 years old. He crossed half the country from Changbai Mountain to S City to seek refuge with his childhood friend Xue Hu Lin Lan, who had already left the mountain. After that, he not only met Mo Yang, a fellow member of the same race who had bullied him when he was 400 years old, but also renewed their relationship with him. He gradually settled down in the city and became another demon clan mixed among humans.