Throughout history, humans have tried to find answers to the question of what is hidden in the Earth beneath us. It was only recently that technology provided the means for seismic measurements and with them, the ability for researchers to map the interior layers of the planet. But, while this provided a rough picture, it left us with many more questions.
Vast, complex structures have been discovered within the Earth's lower mantle — their origin or composition still unexplained. They are linked to the presence of "hot spots", which are zones of volcanic activity not explained by the movement of plate boundaries.
Located near a small town within one of these hotspot regions, a large volcano looms over the horizon. It had long been considered dormant, no signs of activity had been recorded from it for years. That changed when a sudden eruption shook the town. No warning, no indication, just a loud *boom* and a plume of smoke, and it was over as quickly as it happened.
Even stranger, a discovery made on a field at the base of the volcano. There stood a shiny, monolithic black cube, about as big as a one story house. No visible external features, no sound coming from it, until... a hatch opens, and this strange girl whom we know as "Erupt-chan" climbs out.
If she could express herself, she would tell the story of an entire world contained within an enormous deep Earth superstructure, a network of endless winding tunnels and cavernous spaces stretching as far as the eye can see, with large pillars supporting the eons of magma rock above. This enormous artificial structure is inhabited and maintained by the Lithites, an ancient race of mineral-based humanoids, with the purpose of keeping the Earth's core spinning. To this end they've built a massive, powerful and complicated machine, a wonder of the world never seen by human eyes, requiring a great collective effort to keep the rotation stable. The Lithites operate very much like a hive, everyone being expected to work and fulfill their role with almost no regard for the individual. They live this way because it's necessary, because they know that if they fall behind even for a day, unimaginable catastrophe would follow.
And that brings about a society without love, without passion or appreciation for beauty. Things that Erupt-chan felt, but they didn't feel with her. What a waste of time, they'd think. And that is the reason for her exile. Many times she'd get in trouble for daydreaming, for not paying attention, for not working hard enough. So she decided that enough's enough, she had to get out of that place, so she stole one of the escape pods (the "black cube" she was found in) and ascended up through a plume to the surface. That wasn't an easy choice for her. It was a one way ticket. Once she was out... there was no going back, ever. Not because they wouldn't welcome her back, in spite of her treason. But because there simply is no way back down.
They didn't notice she was gone until it was too late, because she had arranged some stones in a human shape in her bed. Classic. And now that she's here, Erupt-chan will have to get used to a very different way of life in a very different world, one that she couldn't have imagined in her wildest dreams. She will need a lot of time to find her place here.