Xiao-Bai, a white snake demon, is sent on a mission to assassinate the Emperor's Taoist advisor, who has been killing snakes en masse in order to achieve immortality and curry the Emperor's favor. Xiao-Bai, however, is attacked by the advisor's lackeys before she can reach him and is subsequently defeated. Luckily, the demonic hairpin she was granted by the Snake Mother is able to save her life at the cost of her memories. Xiao-Bai awakens in the Snake-catcher village, unaware that she is actually a demon or that she is surrounded by her sworn enemies. She meets Xu Xuan, the man who saved her, and is charmed by him. The two set out on a journey to discover who Xiao-Bai is, and learn the secret of her demonic hairpin. The pair is pursued by Xiao-Qing, Xiao-Bai's sister, who has sworn to the Snake Mother to retrieve Xiao-Bai within three days or die trying. As Taoists, demons, and humans collide, a tale of forbidden romance unfolds.

Verta must find a way to escape from the Shura City, in order to rescue her sister Blanca from the monk named Fahai.

The story takes place between the first and second season, where Rimuru confronts the swirling conspiracies in the Coleus kingdom.

The story takes place in the land of Amber Ground, a place of perpetual night only partially illuminated by an artificial sun. Lag Seeing works as a "Letter Bee" (delivery boy) at the "Bee Hive" (a delivery service), with his Dingo, Niche, and her "pet," Steak, traveling with him. He is entrusted with the "hearts" of the everyone in Amber Ground to deliver their packages.