One hundred years ago, aliens landed on a mountain near where a small, white five tailed fox lived. After being stranded on Earth for one hundred 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 finds itself 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 becomes exposed to the hunter, which makes her leave. Of course, the fox hunter tries to hunt her down. Geum-ie tries to save her, but goes down in a lake which makes Geum-ie's soul trapped in a cage as a bird. Yobi tries to save him, but the shadow takes everyone's souls. Yobi defeats the shadow and some ghosts tell Yobi that the number of souls in the lake is always the same and a soul can never go out unless a soul replaces it. Yobi replaces her soul with Geum-ie's.
Some years later, Yobi's soul is released. Yobi becomes human and Geum-ie is still waiting for her.