"APOSIMZ" is a science fiction manga series set in a distant future where humanity inhabits a frozen, mechanized world. The story unfolds on a planet covered in ice, where remnants of human civilization survive within colossal mechanical structures known as "Frames." These Frames are powered by a mysterious energy source called "Aposimz Core," which sustains life and technology in the harsh environment. The narrative centers on Etherow, a young man from a small village who becomes entangled in a conflict that spans the entire planet.

Etherow's life changes when his village is attacked by the "Empire," a powerful faction seeking to control all Aposimz Cores. During the attack, Etherow is mortally wounded but saved by a mysterious girl named Titania, who merges with him using Aposimz Core technology. This fusion grants Etherow enhanced abilities and transforms him into a "Frame Rejector," a being capable of resisting the Empire's control. Titania, who harbors secrets about the origins of Aposimz and the true nature of the Frames, becomes a key figure in Etherow's journey.

As Etherow and Titania travel across the frozen world, they encounter various factions, including the Empire, the "Republic," and independent settlements, each with their own agendas and struggles for survival. The Empire, led by the enigmatic Emperor, seeks to dominate all Aposimz Cores to maintain its power, while the Republic aims to resist this expansion. Along the way, Etherow learns about the history of Aposimz, the origins of the Frames, and the catastrophic event known as the "Great Collapse" that led to the planet's current state.

The series explores themes of survival, identity, and the consequences of technological advancement. Etherow's transformation into a Frame Rejector raises questions about humanity's relationship with technology and the ethical implications of merging man and machine. The narrative is driven by a mix of action, political intrigue, and philosophical undertones, as Etherow and Titania navigate a world where the line between human and machine is increasingly blurred.

Key characters include Etherow, whose journey from a simple villager to a pivotal figure in the conflict forms the backbone of the story; Titania, whose mysterious past and connection to Aposimz Core technology drive much of the plot; and various leaders and soldiers from the Empire and Republic, who represent the competing ideologies and power struggles of the world. The series builds toward a climactic confrontation that challenges the characters' understanding of their world and their place within it.