In a world devastated by humanity's apocalyptic Last War. A massive forest, filled with terrifying creatures and other beasts left behind from the war, covers the land. Small communities of humans live in protected areas. Due to a special weapon used during the war, people spontaneously catch fire when they get close to even small sources of heat. The only safe energy source for humanity is within the bodies of flamelings, and it falls to the brave sickle-wielding firecatchers to hunt them in the depths of the great forest. Among these firecatchers, there are whispers of a "Firecatcher Lord," someone who can harness the power of the thousand-year comet known as the "Wandering Spark." This celestial being has been flying through the sky since it was sent up before the war and is now returning to earth.