During the 3rd Honkai Eruption, the city of Nagazora fell into ruin by the hands of the Herrscher of Thunder. You, who was a victim of said event and was trying to run away from the city with your sister, have fallen into an unknown world. Will you be able to climb back up to the surface and reunite with them? Or will something happen that will change the fate you are in? Or will you walk on a new path akin to being reborn?