In the final episode of "My Demon," Kim Yoo-jung's character Do Do-hee feels as though she has lost Jeong Gu-won again, which causes her to feel guilty and depressed. But after making an agreement with a homeless woman played by Cha Chung-hwa—who is implied to be a supernatural figure—Jeong Gu-won triumphantly returns.
Meanwhile, Do Do-hee has dreams of her past life, where Jeong Gu-won was Seo Yi-sun, and she was Wol-shim. In this dream, she witnesses Seo Yi-sun unknowingly saving Wol-shim's life just by being present.
As the plot unfolds, Do Do-hee discovers that Ju Cheon-suk, played by Kim Hae-sook, saw Jeong Gu-won discussing a contract with her father. This revelation raises questions about her father and the nature of the contract.
Following their reunion, Jeong Gu-won reveals a shocking revelation: Do Do-hee's mother was expecting and in labour when they were unable to locate a hospital. Do Do-hee's father had to make a deal with Jeong Gu-won—who happened to be the child—in order to preserve his wife and pregnant child.
In a different storyline, Noh Suk-min is arrested by the police after Jeong Gu-won approaches Kim Se-ra, played by Jo Yeon-hee, to testify against him.
The conclusion takes an unexpected turn when Ju Seok-hun, rather than Do Do-hee, becomes the chairman of Mirae Group. Do Do-hee's wish to become more self-sufficient and no longer rely on Ju Cheon-suk has an impact on this choice.
In the final scene, Jin Ga-yeong is seen preparing to travel to the United Kingdom but stepping in to help a young girl who is being abused. After Jin Ga-yeong's behaviour resembles that of Jeong Gu-won in the past, she chooses to remain in South Korea.
The last episode wraps up on a positive note, with Jeong Gu-won returning to his role as a demon, seeking justice against wrongdoers, and Do Do-hee continuing her work as the CEO of Mirae F&B. The couple embraces the normalcy of married life, facing daily disagreements, but their love prevails.
The show addresses all lingering questions about Ju Cheon-suk, Do Do-hee's parents, and Jeong Gu-won's involvement in the accident, leaving no loose ends.
Although Netflix and SBS TV haven't officially announced the prospect of a second season, the series ends satisfactorily with the ending.
