Devil Survivor 2: After Story
This game takes place 10 years after the week of hell in the anime Devil Survivor 2: The animation. Those that have watched it you have a leg up sort of those who have not well up to you if you want to watch it or wiki it.
The world as humanity knew it has ended demons have risen and taken over most of it. The only remaining lands humans can safely call home is Japan a gift to humanity given by hero's Hibiki Kuze, Io Nitta, and Daichi Shijima who sacrificed themselves to restore Japan's holy barriers that protect the land and the surrounding seas from the demonic energies of the void. 10 years have passed and the barrier has held thanks in part to the program summoning program Nicaea and the new demon summoner academy headed by the new JP centered Kyoto.
Humanities new mission after 10 long year trapped in exile protecting Japan: retake the world from the demons and slam shut the doors of the void beyond.
