In Japan, the vampire-hunter Saya, who is a powerful original, is sent by her liaison with the government, David, posed as a teenage student to the Yokota Air Base on the eve of Halloween to hunt down vampires. Saya asks David to give a new katana to her. Soon she saves the school nurse Makiho Amano from two vampires disguised of classmates and the Makiho witnesses her fight against the powerful demons...