Demons have been on Earth for thousands of years. The Hashiras have made sure that they don't go out of control. Until one day, an infection goes around and starts to infect people with a virus. This virus turns people into demons. It goes out of control and all of Japan is almost turned into demons. The Hashiras try to keep them contain or find a way to stop them. No matter what, they have to keep these demons inside of Japan. They can't let those demons leave the borders of Japan. If they find a way to escape Japan and go all over the world. Everybody will be doomed. Earth will be doomed. Can the Hashiras do it or will they fall to their demise?