A young, spunky, fearless girl named Sang is searching for the Demon School Hades. She runs into a group of misfit monsters who are ditching classes from the same school. She succeeds in convincing them to take her to the school. Only monsters are allowed at the school so she allows the vampire, Mordicus, to bite her and she becomes a vampire. At the school, Sang meets a girl monster, Notra, who is wearing a ring. Sang also has rings of her own but she wants Notra's ring too but we don't know why. The ring is an engagement ring that has been given to Notra by the chief commander of hell, Baal's son. We also learn of the Mahgae, best described perhaps as "lower-earth", a place where students typically go when they are not in class. The Mahgae also leads to a place called the Redlands. At sunset, the doors to the Mahgae open because nighttime is when the monsters come out to do their work. There are fights between the different cliques of monsters at the school. However, they all come together to fight a mysterious duo that descend upon the school. The duo, a man, Henduh Kyung, and a woman, with very strong powers invade the school in order to seal the door to the school's Mahgae.
Henduh Kyung is also in pursuit of the same mysterious ring. Henduh Kyung and the woman fight the monsters, killing some, injuring others. At the end of Vol. 1, Fatal is seemingly kills the woman, but instead she transforms into a more powerful being and she announces that she intends to honor her league, the Medusa Guild.