One hundred years ago, aliens landed on a mountain near the home of a small, white five-tailed fox. After being stranded on Earth for 100 years, they are ready for a test flight to see if they can return home. The test fails as one of the aliens makes a mistake, and the other aliens tell him to leave.
The runaway alien is taken in by a class of students at the foot of the mountain. There, a teacher named Kang trains students who don't fit in at a regular school. To save the alien, the five-tailed fox takes on the form of a human girl, and joins the school under the name of Yobi.
Staying at the school, Yobi becomes friends with one of the students, a boy named Geum-ie. She enjoys her time with the humans, until a fox hunter appears, as well as a shadow who gives Yobi a device which will allow her to become human by taking the soul from a human.
Yobi: the Five-Tailed Fox has examples of:
- Balancing Death's Books: It's not possible to take a soul from the lake without replacing it with a different soul.
- Bittersweet Ending: Yobi sacrifices her life so that Geum-ie's soul can return to his body.
- Made sweeter when she resurrects into a normal human child.
- Fantastic Foxes: Yobi is based on a gumiho, although in this setting they steal human souls rather than eat their liver.
- Insistent Terminology: Detective Shadow doesn't stalk people, he investigates.
- No Social Skills: The runaway alien would not fit in so well in normal society.
- Pinky Swear: Guem-ee makes Yobi promise to keep a conversation where he shared his favorite son a secret using this. Yobi later has Jong-ee promise to keep her being a fox a secret using the same gesture.
- Pinocchio Syndrome: Yobi can become human by stealing a human soul. She does her best to insist she doesn't she isn't interested because humans are dumb and silly when others bring up the possibility, even though it's obvious she enjoys being apart of the human world.
- Portal Pool: The portal to the land of the dead where souls reside until they are reincarnated looks like a lake when it's open.
- Shout-Out: Yobi and the aliens are seen singing the Russian song 'Zhuravli'('Cranes'), which is well known in South Korea for being used as main theme for popular TV series Sandglass.
- The Soulless: Detective Shadow had his soul stolen a long time ago.
- Voluntary Shapeshifting: Yobi has the ability to change into a girl or whatever form she needs.