Japan's population became infested by a deadly virus called the Akuma entered it's way to Japan overseas by Europe, making humans transform abnormally. They become hostile and go as far as eating the human flesh. In 1800's Japan, many doctors have tried to find the truth about the virus, unitl one day a doctor by the name of Hikaru saw that this virus controls the brain and makes the human have inhumane abilities such as super speed, advanced senses, and powers such as creating fire with ones hand. Over time, natural selection happened and Japan. The humans obtained these natural powers but still didn't have the immortality and lack of emotions like the demons did. Then, a Corps began. It was named Akuma, named after the disease. These people who joined the Corps had abilities like no other and would become slayers of these Demons to protect the land, even something more.. more secretive..