The distant future, 5012. The sudden aerial invasion of Earth by ＜Aliens＞ and their creations ＜Machine Lifeforms＞ led mankind to the brink of extinction. The surviving number of humans who took refuge
by
En`en no Shouboutai (Fire Force)
The Great Disaster (大災害, Daisaigai) is an event that happened two hundred and fifty years before Year 198, with the world mostly consumed in flame, many nations destroyed, and most of the planet rende