Shou Zama, a typical 18-year-old from Tokyo, is summoned to the medieval fantasy realm of Byston Well. There, he is forced into service under the ambitious lord Drake Luft, who aims to vastly increase his influence. Individuals from "Upper Earth," like Shou, possess strong aura power and are assigned to pilot "Aura Battlers"—insect-like mecha created by Shot Weapon, another person from Upper Earth.
Shou's loyalties shift after meeting Marvel Frozen, a young woman rebelling against Drake's political schemes. Realizing the lord's true ambitions, Shou decides to oppose Drake and allies with Neal Given, the leader of the resistance movement. The resistance gains help from Riml, Drake's daughter and Neal's secret lover, who hopes to escape her father's control. As Shou fights alongside his new companions, they risk their lives to prevent the villainous Drake from conquering Byston Well before it is too late.