"Mobile Suit Gundam 0083: Stardust Memory - The Mayfly of Space 1" is set in the Universal Century timeline, three years after the One Year War. The story begins with the Earth Federation testing a new prototype Gundam, the RX-78GP02A Gundam "Physalis," at the Torrington Base in Australia. This mobile suit is equipped with a nuclear warhead, making it a highly dangerous weapon. The Zeon remnants, led by former ace pilot Anavel Gato, launch a surprise attack on the base to steal the Gundam Physalis. Gato, known as the "Nightmare of Solomon," successfully hijacks the unit and escapes into space.

The Earth Federation assigns rookie pilot Kou Uraki to pilot the RX-78GP01 Gundam "Zephyranthes," another prototype unit, to pursue Gato and recover the stolen Gundam. Kou, despite his inexperience, demonstrates determination and skill as he engages in skirmishes with Gato and his forces. The narrative explores the tension between the Earth Federation and the Zeon remnants, highlighting the ideological divide and the lingering scars of the One Year War.

Key characters include Kou Uraki, a young and idealistic pilot thrust into a high-stakes conflict; Anavel Gato, a charismatic and skilled Zeon officer driven by loyalty to his cause; and Nina Purpleton, a Federation engineer and Kou's love interest, who becomes entangled in the unfolding events. The story also introduces other supporting characters, such as Lieutenant South Burning, Kou's mentor, and Cima Garahau, a cunning Zeon officer with her own agenda.

The plot delves into themes of loyalty, sacrifice, and the moral complexities of war, as both sides grapple with the consequences of their actions. The pursuit of Gato and the stolen Gundam leads to intense battles in space and on Earth, showcasing the technological advancements of the era and the strategic maneuvers of both factions. The series builds toward a climactic confrontation, setting the stage for the larger conflict known as the "Stardust Memory" incident, which has far-reaching implications for the Universal Century timeline.