"TO" is a science fiction anime series set in a dystopian future where humanity is on the brink of extinction due to a mysterious phenomenon known as the "Collapse." The Collapse has caused massive environmental disasters, rendering large portions of the Earth uninhabitable and forcing survivors into isolated, fortified cities. The story centers around a group of individuals known as "Drifters," who possess unique abilities to manipulate time and space. These Drifters are recruited by a clandestine organization called the Temporal Oversight Bureau (TOB), tasked with investigating the origins of the Collapse and preventing further catastrophes.

The protagonist, Kaito Arashi, is a young Drifter with the rare ability to rewind time within a localized area. Kaito joins the TOB after losing his family in one of the Collapse's early disasters. Alongside him are other Drifters, each with distinct powers: Aya Fujimoto, who can accelerate time; Renji Kuroda, capable of freezing time momentarily; and Sora Hoshino, who can create spatial rifts. Together, they form a team to undertake dangerous missions into the wastelands, uncovering fragments of the past that hint at the Collapse's true cause.

As the series progresses, the team discovers that the Collapse was not a natural disaster but the result of a failed experiment by a shadowy group attempting to harness time itself. This revelation leads to internal conflicts within the TOB, as some members believe the organization's leadership is hiding critical information. Kaito and his team must navigate these tensions while confronting rogue Drifters and mutated creatures that have emerged in the wake of the Collapse.

The narrative explores themes of survival, sacrifice, and the ethical implications of manipulating time. Key plot points include the discovery of a hidden archive containing records of the experiment, a betrayal within the TOB, and a climactic battle against a rogue Drifter who seeks to exploit the Collapse for personal gain. The series concludes with Kaito and his team making a pivotal decision to reset time, risking their own existence to undo the Collapse and restore the world, though the ultimate consequences of their actions remain ambiguous.