[ Psycho-Pass meets demon/zombie apocalypse. ]

Prime Gate City is where it all had begun. 200 years ago, a mysterious hole appeared in the center of the thriving city, home to over ten million people. Through it, demon-animal hybrids referred to as ‘passers’ have been able to freely enter the human world and wreak havoc on its civilians. In order to deal with these unwanted visitors, the organization PEX, or Passers Exterminators, was formed.

Fast forward to the present in the year 2215, Joseph Harvey is far from the strong and courageous man his late father once was. He’s awfully timid and fearful of everything. Nevertheless, Joseph joins PEX in order to live up to his father’s desire of him following in his footsteps as an exterminator. But things aren't looking so good for him. After several failed missions, Joseph is partnered up with one of PEX’s top officers, the cold and ruthless Luke Kane, in order to redeem himself. This is his last chance to prove that he truly is the son of the legendary exterminator, Reverend Arthur Harvey, and that he too can reach reverence within the organization.