"Kono Hoshi no Ue ni" is a short anime series that revolves around the lives of two young individuals, Aoi and Itsuki, who find themselves in a post-apocalyptic world. The story begins with Aoi, a girl who has been living alone in a desolate, ruined city, scavenging for food and supplies to survive. Her solitary existence is disrupted when she encounters Itsuki, a boy who appears to be from a different world altogether. Itsuki is dressed in a pristine white uniform and possesses advanced technology, including a device that allows him to manipulate time.

As the narrative unfolds, it becomes clear that Itsuki is not from the same timeline as Aoi. He is a traveler from a future where humanity has achieved great technological advancements but at the cost of environmental devastation. Itsuki's mission is to gather data from the past to help his society understand how to prevent their impending collapse. Aoi, initially wary of Itsuki, gradually forms a bond with him as they navigate the challenges of their harsh environment together.

The series explores themes of survival, the consequences of technological progress, and the fragility of human connections. Aoi and Itsuki's relationship evolves from one of mutual distrust to a deep, albeit bittersweet, companionship. Their interactions are marked by moments of tension and tenderness, as they grapple with their differing perspectives on life and the future.

Throughout the series, the stark contrast between Aoi's gritty, resourceful nature and Itsuki's more idealistic, technologically reliant approach is highlighted. This dichotomy serves as a central element of the story, driving both the plot and the character development. The narrative also delves into the ethical implications of time travel and the responsibility of those who possess the power to alter history.

The setting of "Kono Hoshi no Ue ni" is a key aspect of the story, with the ruined cityscape serving as a constant reminder of the world's fragility. The animation effectively conveys the desolation and decay of the environment, enhancing the sense of isolation and urgency that permeates the series.

In conclusion, "Kono Hoshi no Ue ni" is a thought-provoking anime that combines elements of science fiction and drama to tell a compelling story about survival, human connection, and the consequences of technological advancement. The series' concise narrative and well-developed characters make it a memorable entry in the genre.