"Last War of Heavenloids and Akutoloids" is a science fiction anime series set in a distant future where humanity has divided into two factions: the Heavenloids, who inhabit floating cities in the sky and rely on advanced technology for sustenance, and the Akutoloids, who live on the ravaged surface of the Earth, surviving through resourcefulness and resilience. The central conflict arises from the Heavenloids' exploitation of the Akutoloids, using them as a labor force to maintain their utopian lifestyle while denying them access to the sky cities' resources.

The protagonist, Kael, is a young Akutoloid mechanic who discovers a hidden prototype mech buried beneath the ruins of an ancient city. This mech, known as the "Eidolon," possesses unique capabilities that could shift the balance of power between the factions. Kael's discovery draws the attention of both sides, leading to a series of escalating confrontations. Alongside Kael is Lyra, a Heavenloid defector who joins his cause after witnessing the suffering of the Akutoloids firsthand. Together, they form an uneasy alliance, rallying others to challenge the oppressive system.

The narrative explores themes of class struggle, technological disparity, and the moral complexities of revolution. As Kael and Lyra gather allies, they uncover secrets about the origins of the Heavenloids' dominance and the true purpose of the Eidolon. The series delves into the personal struggles of its characters, including Kael's internal conflict over wielding destructive power and Lyra's guilt over her former life as a privileged Heavenloid. The story builds toward a climactic battle that forces both factions to confront the consequences of their actions and the possibility of coexistence.

Supporting characters include Jiro, a seasoned Akutoloid rebel leader who mentors Kael, and Selene, a Heavenloid scientist whose research into sustainable energy becomes pivotal to the plot. The antagonist, General Veyron, represents the Heavenloids' authoritarian regime, driven by a belief in the necessity of maintaining order at any cost. The series balances its action-packed mech battles with moments of introspection, examining the human cost of war and the potential for redemption.