In a long-ago war, humankind set off a devastating ecological disaster. Thriving indistrial societies disappeared. The earth is slowly submerging beneath the expanding Sea of Corruption, an enormous toxic forest that creates mutant insects and releases a miasma of poisonous spores into the air.

At the periphery of the sea, tiny kingdoms are scattered on tiny parcels of land. Here lies the Valley of the Wind, a kingdom of barely 500 citizens; a nation given fragile protection from the decaying sea's poisons by the ocean breezes; and home to Nausicaä.