And then, there was "None"

What if everything and every action you take leads to a disastrous ending. Every small crime no matter how petty acts like a single drop that leads to mass destruction of the very own world you like and live in.
This is what happened, the madness of people collectively destroyed our world. One day the world was fighting within themselves the next moment there was nothing to fight for, while trying to save ourselves we destroyed ourselves. When the world went down in flames it breed more insanity and the result were scavengers and insane people who were born to create more destruction and they went to any limit to prove that.
This is the story of a little child who lost her only parent while trying to evacuate when the scavengers attacked, her story of how she came to know how the perfectly normal world turned out how it is.