Set in a near-future Japan, "AMAIM Warrior at the Borderline" depicts a world where the nation has been divided and occupied by foreign powers, leading to a loss of sovereignty and autonomy. The story centers on Amou Shiiba, a young mechanic living in this fractured Japan. Amou’s life takes a dramatic turn when he encounters Gai, an autonomous AI-controlled mecha known as an AMAIM. This encounter awakens Amou’s sense of purpose, and he becomes determined to fight for Japan’s liberation.

Amou forms a partnership with Gai, piloting the AMAIM to resist the occupying forces. Along the way, he allies with other individuals who share his goal of reclaiming Japan’s independence. Among them is Gashin Tezuka, a former soldier with a deep sense of duty, and Kyouka Maki, a skilled fighter with her own motivations for joining the resistance. Together, they navigate a world of political intrigue, military conflict, and personal sacrifice, striving to unite the fragmented regions of Japan and restore its sovereignty.

The narrative explores themes of nationalism, identity, and the ethical implications of AI and advanced technology in warfare. As Amou grows as a pilot and leader, he faces moral dilemmas and the harsh realities of war, questioning the cost of freedom and the meaning of true independence. The series balances intense mecha battles with character-driven drama, highlighting the struggles and motivations of its diverse cast. Through its depiction of a divided Japan and the fight for liberation, "AMAIM Warrior at the Borderline" presents a story of resilience, unity, and the enduring human spirit in the face of oppression.