A mysterious warning is delivered to a woman living alone in Tokyo when her brother, who has been away at college, unexpectedly arrives at her apartment. He tells her that a great disaster is coming and that the city will be destroyed the next day. She dismisses this as nothing more than an unfounded rumor circulating on the internet, and she refuses to believe that the person in front of her could be her sibling. Before vanishing, the young man declares that he is the omen of the coming calamity and that she must decide how to react to the event.

The following day, strange orange spores appear and descend upon Tokyo. These particles coalesce in the sky to form an enormous humanoid creature, a Giant God Warrior. The being slowly hovers over the metropolis before descending to ground level, shrinking to the size of a large building as it lands. The God Warrior observes its surroundings for a moment. It then opens its mouth to reveal a complex weapon, unleashing a devastating proton beam along with red projectiles that tear through the cityscape. The attack obliterates Tokyo in a massive conflagration, leaving a mushroom cloud over the ruins.

The narrator, the woman who received the warning, explains that gods are not only creators but also destroyers, which is why humans worship them. She states that the world has a set lifespan and that the Earth itself has called upon the God Warriors to initiate the Seven Days of Fire, an event that will destroy most of human civilization and recreate the planet's ecosystem. As she speaks, an entire army of Giant God Warriors appears, walking with spear-like objects through the blazing ruins of Tokyo.

The setting is a contemporary Tokyo that exists as a parallel or prequel timeline to the world of Nausicaä of the Valley of the Wind. The short film serves as a live-action depiction of the apocalypse that occurred one thousand years before the events of that animated feature, showing the destruction of modern industrial civilization. The narrative is framed by the philosophical monologue of the unnamed female narrator, voiced by Megumi Hayashibara, who reflects on humanity's desire to prolong the world's existence against the natural order of destruction and renewal. The Giant God Warrior itself is voiced by Hayao Miyazaki, co-founder of Studio Ghibli. The film relies on practical special effects and miniature work rather than computer-generated imagery, giving the destruction a tangible, physical weight. The theatrical version adds CGI wings to the God Warriors in the final scene and enhanced sound design. The short concludes with the implication that this event is only the beginning of a larger extinction-level catastrophe, the Seven Days of Fire, which will reshape the planet.