Mikoto and Takeru both belong to the [Black Cat Demon Extermination Brigade]. One day, they are sent to the prestigious Seisen Girls' Academy in order to exterminate the youmas that's been sighted on the school's grounds. They infiltrate the school as one of its students, but as they continue to fight demons night after night, they discover dark secrets lurking around the place. Just then Takeru is afflicted by a curse and the two are attacked. To save her sister from the clutches of lust, Mikoto ventures forth right into the enemy's den, only to witness the female students of the academy giving themselves away to pleasures of flesh. Limbs entangled, the demonic tentacles dance wildly. While indulging in one another, the two sisters are going to be sacrificed, each and every nook and cranny of their bodies to be used to breed all kinds of youmas…