"Skelter+Heaven" is a short anime series set in a dystopian future where humanity faces extinction due to the emergence of monstrous creatures known as Angels. To combat this threat, the government deploys advanced humanoid weapons called Shells, designed to fight the Angels and protect the remaining population. The story centers on two Shells, Ichi and Ni, who are tasked with leading the defense against the Angels while grappling with their own humanity and purpose.

Ichi and Ni are part of a larger group of Shells, each with unique abilities and personalities. Despite their mechanical origins, they exhibit human emotions and form bonds with one another, raising questions about their identity and the ethics of their creation. As the Angels grow more powerful and numerous, the Shells face increasingly difficult battles, testing their limits and resolve. The narrative explores themes of survival, sacrifice, and the blurred line between human and machine.

The series delves into the psychological toll of constant warfare on the Shells, particularly Ichi and Ni, who struggle with their roles as weapons and their desire for a normal life. The government’s manipulation of the Shells and the moral ambiguity of their mission add layers of tension to the story. As the conflict escalates, the Shells must confront not only the external threat of the Angels but also the internal conflicts arising from their programmed obedience and growing self-awareness.

The plot is driven by the relentless progression of the war, interspersed with moments of introspection and character development. The dynamic between Ichi and Ni serves as the emotional core of the series, highlighting their camaraderie and shared burden. The series concludes with a climactic battle that forces the Shells to make critical decisions about their fate and the future of humanity, leaving a lasting impact on the narrative.