Worst(1970)

One day, a juvenile delinquent, Eiji Razor, instinctively sensed danger and hid himself in the basement of an abandoned warehouse. When he went outside after a long rain, he saw a town taken over by the Worst, nocturnal creatures that are born from human corpses and can regenerate even after being dismembered. A dreadful virus was mixed in the rain that killed humans and turned them into Worst. While fighting off the Worst, Eiji found survivors including Taku Maejima, a young boy, Harry, an American soldier, and Tozaki, a delinquent student, and they hid in the Kasumigaseki Building as a fortress.