"End of the World" is a dystopian anime series set in a future where humanity faces extinction due to a mysterious phenomenon known as the "Collapse." The Collapse causes entire regions of the world to vanish without warning, leaving behind desolate voids. As the phenomenon accelerates, governments and societies crumble, leaving survivors to navigate a fragmented and perilous world. The story centers on a group of individuals who band together to uncover the truth behind the Collapse and find a way to prevent the complete annihilation of humanity.

The protagonist, Kaito, is a former scientist who once worked on a secret government project related to the Collapse. Haunted by the loss of his family during an early event, Kaito becomes determined to understand the phenomenon and reverse its effects. He is joined by Aya, a resourceful and pragmatic scavenger who has survived on her wits alone, and Ren, a former soldier with a deep sense of duty and a tragic past. Together, they form an uneasy alliance, driven by their shared goal of survival and the hope of finding a solution.

As the group travels across the decaying remnants of civilization, they encounter other survivors, some of whom are hostile, while others offer temporary alliances. The series explores themes of trust, sacrifice, and the fragility of human connections in the face of existential threats. The characters are frequently tested by moral dilemmas, such as whether to prioritize their own survival or risk everything to help others.

The narrative unfolds through a series of episodic encounters, each revealing more about the Collapse and its origins. Flashbacks provide insight into the characters' backstories and motivations, while cryptic messages and artifacts hint at a larger conspiracy. The group discovers that the Collapse may be linked to an experimental technology developed by Kaito's former colleagues, raising questions about humanity's role in its own downfall.

As the series progresses, the stakes escalate, with the group facing increasingly dire challenges, including rogue factions, environmental hazards, and the ever-present threat of the Collapse itself. The final arc culminates in a desperate race against time to uncover the truth and enact a plan that could either save what remains of the world or hasten its end. The series concludes with an ambiguous yet poignant resolution, leaving the fate of humanity open to interpretation.