Conquering the EX World

There exist a vast number of worlds, all having both Demons and Gods. The Gods in the worlds recruit heroes while demons send one of themselves to be that world's demon lord. In the Demon Realm, all of the demons have gathered together in front of Lucifer, the Demon among demons. There, they wait to see the score of the next world that needs a demon lord, but an uproar starts due to the score results - EX rank. Since this only happened once, everyone was unsure what to do. This is when Lucifer comes up with an idea and sends one of the 'weakest' demons, Kenta. Without any say, Kenta gets sent to the hardest world that the Demonic Realm has ever had. That said, what he finds out in the world surprises him... How will Kenta survive in the EX world?