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.

The search for the Treasurebeast Orbs scattered across Caldina leads Hugo and AR-I-CA to the great city of Cortana. This cosmopolitan center of commerce is no doubt a jewel of the desert, but few things in this city have as much value as the Orb said to have arrived here—one said to bestow the coveted power of immortality. With such rumors spreading far and wide, it would be foolish to think that Hugo and AR-I-CA would be the only ones in pursuit of this boon. A knight of ice, a soaring songstress, a bloodstained child, and a Master of death converge upon the poisoned oasis, heralding the coming of a brand new possibility.

One thousand Japanese high school students are suddenly thrust into an unfamiliar world rife with dangerous monsters. Their survival becomes dependent on those who awaken to unexplainable powers. Majima Takahiro, a normal second-year student, does not get any such power. Instead, he joins the majority of students building the homestead. But when a group of empowered students revolt, Takahiro is left wandering the forest on the verge of death. Having lost all faith in humanity, he finds salvation from an unlikely source: monsters!

The monster attack has left Fort Tilia in ruins. Since they can no longer defend the fortress or stay there in safety, Takahiro and the remaining survivors leave to escape the Woodlands. Their destination is the Third Company's home of Aker. Trouble follows close behind them, though. The Skanda, a cheater with overwhelming power even among the students, receives news that Takahiro might've been the one behind the monster attack. Thus she begins her pursuit, ready to bring him and his monsters to justice.

After arriving safely in the imperial capital, Takahiro meets the exploration team and receives an invitation to join them. However, with Mitarai’s objection and the discovery that Okazaki was one of people responsible for Draconia’s destruction, Takahiro decides to turn it down. He then returns to his room to comfort Mana over her argument with Mitarai, after which the entire group is suddenly whisked away by the power of the Fairy Ring. Takahiro finds himself stranded with Mana, separated from the others in a mysterious and monster-infested labyrinth. Takahiro’s servants are scattered throughout the rest of the deadly maze, and finding their way back to his side won’t be easy, for more than just monsters lurk in these winding halls...

After being teleported to a fabricated world, Takahiro is isolated from his companions. Mikihiko suddenly appears and stabs him, abducting Mana in the process. Takahiro steels his resolve to go rescue her. The stage is set as the Holy Order pits the two best friends against each other in a battle to the death. Meanwhile, things are on the move back in the capital as Kei makes an unexpected discovery, and Mana finds herself faced with the mastermind behind the whole incident, Marshal Harrison Addington, the knight among knights.

Escorted by the elven knight Shiran, Majima Takahiro and Lily arrive at a fortress within the monster-filled forest. There, they meet members of the first expeditionary force and Takahiro’s best friend Mikihiko. Not everything is as it seems, however. As the two of them begin to learn more about this world and its inhabitants, they must closely guard their secrets from all those around them. Meanwhile, Gerbera, Rose, and Katou Mana remain hidden in the forest. They continue to keep a watchful eye on the fortress, but an unexpected event befalls them...