The Devil of Humanity

In a dark and hopeless world, there are monster roam around the street. They kill, eat and rape anyone who oppose them... In this world, there are a unit call "Taimanin" aka "Anti-Demon Ninja". They are the one that keeping humanity from existence or worst... Becoming the Demon's slave... But their effort isn't enough... Humanity is starting to lose hope... Until... Something that even the demons refer as... "The Devil" appear.