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?