Kufa, a youth, is appointed to serve as a mentor to Mareida, a troublesome girl born into the household of a duke, in order to assess her inherent abilities. In a society where only aristocrats possess the authority to battle the monsters known as mana, those who hold the power are limited. Nonetheless, if Mareida proves to be unskilled, Kufa's assignment possesses a sinister dimension, since he is tasked with terminating her.