Five thousand years ago, humanity had stood at an unprecedented peak.
Back then, humanity had long since ceased to be satisfied with the world beneath its feet. They crossed the barriers between worlds, stepped into one otherworld after another, and established colonies, cities, and resource bases across countless planes.
That had been humanity's golden age.
Until the arrival of that disaster.
For reasons unknown, that calamity shattered the human powers of the Main World, weakening their control over other worlds and plunging the whole of human civilization into civil war.
Yet humanity's disaster had not ended.
One day, every cross-world passage suddenly lost its stability.
The colonies, already thrown into chaos after losing support from the Main World, fought and slaughtered one another over limited energy, food, and shelter.
Once the cross-world passages collapsed, more and more unknown worlds began invading in reverse. Humanity, having lost its defensive lines, could only fight the creatures of other realms head-on.
Beset by troubles within and without, war after war claimed countless powerful figures, reduced cities to ruins, and left the living struggling for survival amid the wreckage.
The once-glorious human civilization was dragged completely into the Abyss.
Later, people collectively called those darkest years—the "Disaster Era"!
"Ah!"
Early that morning, Jack suddenly opened his eyes and jolted upright in bed.
He gulped down breaths, his forehead drenched in cold sweat.
Only after quite a while did he recover from that suffocating feeling of being on the brink of death.
That dream again.
The scene in the dream was still so clear it drove him to despair: the collapsed shelter, the raging flames, the glaring blood on the ground, and that mutated beast that had rammed through an alloy wall.
His father had fallen in a pool of blood, while his mother desperately