Misa Kuroi, a Japanese high school girl with Satanic powers, mysteriously appears in various high schools. A weird girl with smooth long hair, she always wears a sailor suit uniform, but never actually studies. Carrying a dagger and a heavy leather bag, she uses her powers to eliminate the evil forces that thrive on deadly sins of the human race. Her characteristic chants are," Eko eko azarak, eko eko zamerak, eko eko kamedios..." Her parents were changed into wooden miniatures and her beloved sister is captured by the demons. Her ultimate aim is to cleanse the earth and rebuild her broken family.