Cows have died out and are now made using human DNA. They can speak and look similar to humans, but people still eat them and treat them as cows. After his father was eaten, Lamda the cow decides to run away. Unfortunately he is caught, but before that he helps a little boy, Mitsuhiko. The boy then insists Lamda become his servant instead of being eaten. When the Black Plague hits Mitsuhiko, he is in danger of dying because the only cure is cow's meat and every cow except Lamda is gone.
Extra chapter from X-Day Volume 2.