Shou Zama is an ordinary 18-year-old from Tokyo who finds himself summoned to the medieval fantasy world of Byston Well. Upon arrival, he is put into service under the ambitious lord Drake Luft, who seeks to greatly expand his power. Those like Shou who come from "Upper Earth" possess strong aura power and are ordered to pilot "Aura Battlers," insectoid mecha designed by a man named Shot Weapon, who also came from Upper Earth.