Riru, a low-level demonic incubus reputed to be the weakest in the Pandemonium. On the day of the coronation of Baal, the new demon king, Riru falls in love with him at first sight. Riru, who has been longing for Baal, hears from his friend that Baal will close the door to the human world, the source of energy for the incubus, and hurries to the Devil’s Castle. Riru, who succeeded in infiltrating the Devil’s Castle, is in danger of being discovered and killed by Baal in front of the door, and Riru, who is terrified, unknowingly casts a spell on Baal