At Yokota Base in Japan, American soldiers stand guard at the brink of the Vietnam War. Although they fear the enemy outside their base, an even more dangerous enemy waits within - bloodthirsty vampires walk among them. Appearing human, the beasts lurk in secret among the soldiers, waiting for the moment to attack. Saya, a fierce and beautiful vampire hunter, is sent to lead a team of undercover agents whose mission is to decide who is human and who is not, and wipe out the vampires before they can wipe out the base.