Masamune, a third-year middle school student, lives in a town where all the exits have been sealed off due to a sudden explosion at a steel mill, causing time to stand still. Residents are forbidden from making any changes and spend their suffocating days in the hopes of returning to normalcy someday. One day, Masamune's mysterious classmate Mutsumi guides him to the fifth furnace of the steel mill, where they encounter a girl who cannot speak and resembles a wild wolf. The meeting between the two girls and Masamune disrupts the balance of the world, and the unstoppable "impulse of love" from boys and girls tired of their daily lives begins to destroy the world. (Source: MAL News)

In 2035, an incident known as “The Burst” occurs at a Japanese research facility, giving birth to the rapidly expanding, consuming, and self-replicating "Matter." Snaking its way through the remains of dams and military facilities in the Kurobe Gorge, the hostile Matter is besieged by task forces trying to prevent it from reaching the ocean and mercenaries seeking the truth behind its existence. Aiko Tachibana lives under constant medical surveillance after being rescued from the Matter. She spends her days waiting out her recovery by making paper planes. Soon, her daily life at school is disturbed by the arrival of transfer student Yuuya Kanzaki, who proceeds to point out a number of inconsistencies regarding her body. Why is she never injured, and why does she suddenly no longer need her wheelchair? He claims that there is more to her existence than she has been led to believe, and that she alone holds the key to ending The Burst. With many factions now interested in Aiko, she and Yuuya must gather allies and embark on a dangerous pilgrimage into the heart of the infested gorge before the net can close around them. To escape the conspiracy moving against them, the pair must face off against the Matter—an enemy that flows like water.