Introduction: The story takes place in a post-apocalyptic future where humanity lives in the undergrounds of Earth after an alien invasion. The few survivors formed a network of mutual aid to survive, but the aliens still seek them out. When the invaders finally find the human hideout, they suddenly retreat with inexplicable fear. The survivors discover that the cause of the aliens'' fear is an earthquake that devastated the planet. Now, they are determined to rebuild what remains of Earth and fight for their survival....