Two worlds are rapidly expanding and colliding within the inside of the world.
This can happen; new worlds can be born within the interior of an existing world. There's a hypothesis that black holes are the offspring of the universe, new universes generated within the interior of the cosmos. Although this hypothesis isn't entirely rigorous, it's indeed possible—just as a mother's body can birth a human, the material and space-time structure within the universe are selectively optimized for the creation of black holes, its progeny.
But the current situation is completely opposite to the birth of progeny from the mother.
Two immensely powerful beings, who don't need the protection of the world, greedily seize control of surrounding worlds at a speed faster than light and instantly form two vast and completely opposing worlds, extending their power toward each other without hesitation.
It's not just about plundering the world, but also seizing the other.
[Cave Heaven Expansion]
