[4][5] From November 18 to December 4, it also aired a three-part spin-off titled Tale of the Nine Tailed: An Unfinished Story (Korean: 구미호뎐: 못다한 이야기; RR: Gumihodyeon: Motdahan i-yagi),[5] centering around Lee Yeon's younger brother Lee Rang and his accomplice Ki Yu-ri.

He works with Taluipa (Kim Jung-nan), an agent in the Afterlife Immigration Office and the protector of the Samdo River, to eradicate supernatural beings that threaten the mortal world.

He lives in the city where he is assisted by his loyal subject, veterinarian, and fellow Gumiho, Goo Shin-joo (Hwang Hee).

It is then revealed that as a child, on her ninth birthday, Nam Ji-ah was involved in a road accident in which her parents were supposed to be dead.

She died at the hands of Yeon while trying to save him from Imoogi, an evil earth dragon who wanted to inhabit the body of the guardian mountain spirit.

By abusing his powers, a heartbroken Yeon stopped the boat carrying Ah-eum across the Samdo River, kissed her, and gave her a fox bead while asking her to promise to be reincarnated.

The poster of the television series was unveiled by Lee Dong-wook and Jo Bo-ah on September 9, 2020, which was termed as "Rhapsody of intense affection".