The Fuzuki family has been exterminating demons for generations. The priestesses who were born there, the elder sister Haruka and the younger sister Haruna.

One day, she learned that the seal of the evil god had been broken. Haruka tried to exterminate it. However, she is captured by the tentacles of an evil god and turned into his servant.

After swearing allegiance to the evil god, "Haruka" returns to Fuzuki's house. Leading your beloved sister to the evil gods...