On an ordinary day, a mysterious catastrophe struck Earth, turning the world upside down and claiming the lives of most of humanity within a short span of time. But that was not the end of their suffering. As the survivors struggled to overcome that tragedy, they were confronted by an even greater threat—invaders from beyond their world, driving humanity into a long series of brutal wars and bloody battles. After years of bloodshed and loss, the conflict finally ended with humanity's victory. Yet the world they had fought so hard to protect was no longer fit for life. Amid ruined cities, dried-up oceans, and a wasteland stalked by monsters and predators, the remnants of humanity struggle to find a place where they can survive. Then, in the midst of this desperate age, a way to escape their dying world is discovered. And so begins the journey of a group of survivors as they set out in search of a new homeland.