"Garasu no Kodou" is a manga series set in a world where humanity is plagued by a mysterious disease known as the "Glass Syndrome," which causes individuals to gradually turn into glass. The story centers on a young girl named Ruri, who is immune to the disease, and her journey to uncover the truth behind the syndrome while navigating a society on the brink of collapse. Ruri's immunity makes her a target for various factions, including the government, which seeks to exploit her for research, and rebel groups that view her as a symbol of hope.

The narrative begins in a dystopian city where the government enforces strict quarantine measures to control the spread of Glass Syndrome. Ruri lives a secluded life with her adoptive father, a scientist who has been studying the disease. When her father is captured by government agents, Ruri is forced to flee and encounters a group of rebels led by a charismatic yet enigmatic figure named Shuu. Together, they embark on a mission to infiltrate government facilities, rescue her father, and uncover the origins of the disease.

As the story progresses, it is revealed that Glass Syndrome is not a natural phenomenon but the result of human experimentation. The government had been conducting secret experiments to create a "perfect" human race, inadvertently triggering the syndrome. Ruri's immunity is tied to her unique genetic makeup, which holds the key to reversing the disease. However, her immunity also makes her a pawn in a larger power struggle between the government and the rebels, both of whom seek to control her for their own agendas.

The manga explores themes of survival, morality, and the consequences of scientific ambition. Ruri's character evolves from a sheltered, naive girl to a determined and resourceful individual who must confront the harsh realities of her world. Shuu, the rebel leader, serves as both a mentor and a foil to Ruri, challenging her beliefs and pushing her to question the motives of those around her. The government is portrayed as a cold, authoritarian entity willing to sacrifice individuals for the greater good, while the rebels are depicted as morally ambiguous, driven by both altruism and personal vendettas.

The plot is driven by a series of escalating conflicts, including daring rescues, betrayals, and revelations about the true nature of Glass Syndrome. The climax involves a confrontation at a secret research facility, where Ruri must decide whether to use her immunity to cure the disease or destroy the facility to prevent further exploitation. The ending leaves room for interpretation, with the fate of humanity and the characters left uncertain, reflecting the series' overarching themes of hope and despair in the face of existential threats.