From: Easy Going Scans

When Ah-ryoung was only a baby, her mother made a pact with a demon named Nachal, who would claim Ah-ryoung's body once she turns 15.
She has inherited her mother's considerable spiritual powers but that "gift" that allows her to see ghosts even from an early age, has made her an outcast for the other kids.
She has finally turned 15 and it’s now time for the demon to claim her body... but then an accident happens...

Shin Gumiho (Shin meaning "new" and Gumiho meaning "old fox") begins with its origins based on Korean folklore. The 9-tailed demon fox, Gumiho, wishes to change into a human in order to keep her promise to the one she loved. However, right before she turns into a human, a vengeful demon-purger arrives and seals her into a sword. Now, in present day Korea, a young boy has found the sword and its contents. Gumiho is reawakened, but what will she do now?