At Youkai Academy, Tsukune Aono, the lone human amidst a horde of monsters, finds himself entangled in a web of affection from various enchanting women: the seductive succubus Kurumu Kurono, the witch Yukari Sendou, the obsessive yuki-onna Mizore Shirayuki, and the gentle vampire Moka Akashiya, harboring a hidden sinister side once her rosary is unclasped. The tranquility of the academy is disrupted by Moka's sister, Kokoa Shuzen, who resents Moka for concealing their true sibling within the rosary, determined to unleash Moka's darker persona. Kokoa's reckless pursuit, however, threatens more than just sibling dynamics at Youkai Academy.