A great forest, infested with flameling creatures and other fallen beasts, covers the world, and pockets of humanity live in small protected communities. Due to a special weapon used in the Last War, human beings spontaneously burst into flame when merely getting close to a small source of fire. The only safe energy source for humanity lies within the bodies of flamelings, and the duty to hunt them falls to the sickle-wielding firecatchers who brave the depths of the great forest. Touko, a young girl from a paper-making town, finds herself in the forbidden forest, assailed by flamelings, when a flamecatcher rushes to protect her. In another place, a young capital-born boy named Koushi shelters his younger sister after losing his mother to factory poison.