The world was once again a wasteland. Miss Kim told Han all about how zombies suddenly appeared out of the blue one day and began attacking people in the city. The city authorities tried to evacuate people by sea and air but they were easily repelled by the zombies and killed. The only place where refuge remained was the underground. It was a large labyrinth built under City C a long time ago. People once used it to transport drugs and food without being caught by the authorities, but now it was used as a refuge for survivors.
Down here, the only law was money and power. In the darkest moments, the head of the underground came and declared that they would be starting a tournament with the greatest fighters they had. People who were not going to fight in it would have to pay a large sum monthly to keep out of the cage, but if you didn't pay then you would have to fight.