Blood The Last Vampire (2000)

In Japan, the formidable vampire slayer Saya is dispatched by her government contact, David, to blend in as a high school student at Yokota High just before Halloween. Her mission is to track down and eliminate vampires lurking among the students. Saya requests a new katana from David to aid in her quest. During her investigation, she rescues the school nurse, Makiho Amano, from two vampires posing as fellow students, and Makiho becomes a witness to Saya's fierce battle against a menacing demon.