From dark (2007)

Under Professor Furuchi, Kawano has been engaged in the development of a new vaccine against the unidentified substance which fell from outer space. People infected with it begin to attack other human beings for blood. The one and only way to prevent the attacks of the infected people is getting vaccinated and becoming one of them. Kawano has volunatrily chosen to be infected for absorbing in the research. His girlfriend Taeko is worried about him and visits the laboratory. She tries to rescue Kawano in cooperation with his friend Sawamura, a medical practitioner in town: meanwhile, the mysterious black substance has started pouring down from the sky...