The project's story begins with the "Day of Purgatory" marking the arrival of Mist, a calamitous mist that becomes the worst disaster in known history. Life crumbles with its arrival, and strange beasts emerge from it. Humanity seems to be on the path to extinction. 70 years after the Day of Purgatory, the Valks Kingdom begins "Mist Gear," a project that will restore hope to humanity.