In the year 2061, Japan became an occupied territory. The subjugated Japanese people lived in a dreary world under constant oppression, as they were divided and ruled by four major world economies. Japan became the front line of the world where AMAIM, a humanoid drone mecha deployed by different economies, roamed the streets. One day, Shiiba Amou, a boy who loves machines, meets "Gai", an autonomous AI. This led Amou to throw himself into the fight for Japan's independence, riding the AMAIM "Kenbu" that he assembled himself.