Fire Force

From the introduction: 250 years ago, the world was rent apart in an event known as the Great Cataclysm. Amid the flames of devastation, entire continents were torn apart and reduced to ashes, with some landmasses erased entirely amidst inexplicable rifts in space. Countless millions died, and many who survived must have wished they had not, for alongside the Cataclysm came Spontaneous Human Combustion.