In a world shrouded in darkness, where demons run rampant, a young man named Hisago Harukawa, once forced into committing crimes under the threats of demons, sets his sights on his next target: a suspicious woman who calls herself Darwin, proponent of Evolution.! But this encounter changes everything, Hisago is pulled into a battle to send demons back to the depths of he**!! To survive, he must evolve. A devil-hunting fantasy of atonement begins!!!