Majima Takahiro and his friends survive the ordeal inside the labyrinth and learn the truth about the world. Their very existence threatens to trigger another Grand Calamity, a world-ending event. Fortunately, they also possess the knowledge to preempt such a catastrophe. Set to return to Aker to accomplish that goal, they are forced to go back to the capital when they are informed that the world faces more than one apocalyptic threat.