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 High School 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 Makiho witnesses her fight against the powerful demons.

The anime's story is set in 2027, one year after the end of the fourth non-nuclear war. New Port City is still reeling from the war's aftermath when it suffers a bombing caused by a self-propelled mine. Then, a military member implicated in arms-dealing bribes is gunned down. During the investigation, Public Security Section's Daisuke Aramaki encounters Motoko Kusanagi, the cyborg wizard-level hacker assigned to the military's 501st Secret Unit. Batou, a man with the "eye that does not sleep," suspects that Kusanagi is the one behind the bombing. The Niihama Prefectural Police detective Togusa is pursuing his own dual cases of the shooting death and a prostitute's murder. Motoko herself is being watched by the 501st Secret Unit's head Kurutsu and cyborg agents.

In the year 2027, a year following the end of the non-nuclear World War IV, a bomb has gone off in Newport City, killing a major arms dealer who may have ties with the mysterious 501 Organization. Public Security official Daisuke Aramaki hires full-body cyber prosthesis user and hacker extraordinaire, Motoko Kusanagi, to investigate.ovagirls with gunsPlot summaryAdd synopsis