Beyond the boundaries of the supernatural lies a realm ruled by Flame Demons, fierce creatures that have taken over the entire world. Human survival depends on the Fire Hunters, who stand as their only defenders. Koushi is a skilled tracker who roams the dark, dense forests inhabited by these beasts. In one of his expeditions, he saves Touko - a young inhabitant of a nearby village - from a lethal attack. As fate would have it, their meeting was not a coincidence, and a new journey begins for them.