Shi Yeon is a Nine-Tailed Fox living undercover in the human world. By day, Shi Yeon is an employee at a natural history museum. By night, she's a top-ranking woman warrior in the Nine-Tailed Fox clan, charged with preserving the delicate balance between man and fox. But her world is sent spinning when an atrocious serial murder - where the victims have had their internal organs gouged out - is uncovered. Detective Min Woo believes the murders may relate to the organ trafficking trade, and goes undercover in a seedy organ smuggling ring. But Min Woo's cover is blown, and it's only through the intervention Nine-Tailed Fox warriors, Mu Young and Shi Yeon that he's able to survive! But he's seen their true identities as Nine-Tailed Foxes, can he be allowed to live?
Yamihara Kokoro and Asada Toramatsu live in a town that is quite peaceful, until a serial murder case happened where the bodies all had their blood drained out. Five years have passed but the case remains unsolved. Meanwhile, Kokoro and Toramatsu have been in a relationship for a year, but are unable to get married as they are keeping a serious secret from each other. Kokoro is actually a vampire. However, she does not attack humans and live modestly. Toramatsu is a popular resident in the town and is trusted by many. After getting a divorce, Toramatsu got drunk and went back to his old house, where he met Kokoro, the current occupant. As the two continue to keep their secrets hidden, a horrific murder occurs once again in the town.
Lee Seul Bi is an angel who is sent to Earth to look after Shin Woo Hyun, who lives with his grandmother and carries emotional scars from being abandoned by his parents. Despite his cold demeanor, Woo Hyun is popular in school because of his good looks and singing ability. When his best friend, Hwang Sung Yeol, finds out a secret that ties them together and also develops feelings for Seul Bi, who is posing as a fellow student at their school, the best friends turn into rivals.
