Japan—In the near future.
Swarming with all manner of demonic beings.
An unspoken rule of "mutual non-aggression" had been followed since the ancient times, but this began to show signs of collapsing when people strayed from the path of righteousness. Humans and demons colluded to form criminal organizations and corporations that acted in the shadows. Thus, the world descended into chaos. However, those who sought the right path were not powerless either. The government of the time assembled a group of ninja. They would be the humans who could stand against the demonic forces, opposing the deviants' evil.
And they were known as... "Taimanin"———