Set in a 2023 where humanity has achieved rapid interstellar travel, Gunbuster depicts an Earth unified by a singular existential threat: the 'Space Monsters.' The world has shifted into a high-intensity military footing, funneling resources into the Luxion fleet and elite training academies to produce pilots capable of wielding massive Buster Machines. Earth remains the political and emotional anchor for the characters, though it becomes increasingly alien to them as they age at a slower rate than those they left behind.

The film’s dynamics focus on the marriage of hard physics and emotional trauma. Unlike many of its contemporaries, the narrative leans heavily into the Lorentz transformation, where minutes in combat translate to months or years on Earth. This creates a society where the defenders of humanity are perpetually out of sync with the civilization they protect, leading to a profound sense of cultural and personal dislocation as Earth progresses through decades in what feels like days to the protagonists.

Regarding technological predictions, Gunbuster is noted for its early conceptualization of scientific realism within the mecha genre, specifically its handling of time dilation and the use of black holes as power sources. While we have not reached 2023's depicted level of space colonization, the film's vision of machine-human interfaces and exoskeletal suits mirrors current developments in haptic feedback and robotics. However, the film's 2023 is an alternate timeline where the discovery of faster-than-light travel in the late 20th century accelerated human expansion far beyond our current reality.