"World's End and Apricot Jam" is a manga series that blends elements of science fiction, mystery, and psychological drama. The narrative centers on a world where humanity faces an existential crisis due to a mysterious phenomenon known as the "World's End." This event causes time to fracture, creating parallel realities and fragmented timelines. The story explores the consequences of this temporal collapse, focusing on the interconnected lives of its characters as they navigate the chaos.

The protagonist, a young woman named Aoi, works as a researcher investigating the anomalies caused by the World's End. Her life takes a dramatic turn when she encounters a strange, sentient entity that manifests as a jar of apricot jam. This entity, which calls itself "Jam," possesses the ability to manipulate time and space, offering Aoi glimpses into alternate realities and potential futures. As Aoi delves deeper into the mysteries of the World's End, she uncovers unsettling truths about her own past and the nature of existence.

Supporting characters include Aoi's colleagues, who are also grappling with the ramifications of the fractured timelines. Among them is Ren, a pragmatic scientist who serves as a foil to Aoi's idealistic nature, and Yuna, a mysterious girl with a personal connection to the World's End phenomenon. The relationships between these characters are tested as they confront ethical dilemmas and the moral ambiguity of their actions in a world where cause and effect are no longer linear.

The plot unfolds through a series of interconnected vignettes, each exploring different timelines and realities. These segments reveal the broader implications of the World's End, including the psychological toll on individuals and the societal collapse that ensues. Themes of identity, memory, and the fragility of human connections are woven throughout the narrative, as characters struggle to reconcile their fragmented selves across multiple timelines.

As the story progresses, Aoi and her companions uncover the origins of the World's End, which are tied to a failed scientific experiment aimed at transcending the limitations of time. The climax involves a confrontation with the forces behind the experiment, forcing the characters to make difficult choices about the future of their fractured world. The resolution leaves lingering questions about the nature of reality and the possibility of redemption in a universe where time itself is broken.