Setting: in a future in a city dominated and polluted by human.
irony: though people in the city has been destroying the natural and city they were destroyed. Meanwhile, though the main character hesitated to destroy the natural and city, he was saved by natural.
Theme: don't fight against the natural and save natural. Otherwise I will be punished by natural.
Conflict: human versus natural.
Symbol: the mass mortality of human symbolize what we would face in the future if we keep polluting the earth.