"Gachiakuta" is set in a dystopian world where society is sharply divided between the wealthy elite living in the floating city of "The Garden" and the impoverished masses struggling to survive in the polluted wasteland below, known as "The Abyss." The narrative centers on Rudo, a young boy who is unjustly accused of murder and subsequently exiled from The Garden to The Abyss. In this harsh environment, Rudo discovers that the trash discarded by The Garden contains powerful, sentient artifacts called "Gears," which can be wielded by certain individuals known as "Gear Users."

Rudo, who possesses a unique ability to communicate with Gears, joins a group of rebels called the "Gachiakuta," who fight against the oppressive regime of The Garden. The Gachiakuta aim to uncover the truth behind the corruption and exploitation perpetuated by the elite, while also seeking to improve the lives of those in The Abyss. As Rudo delves deeper into the mysteries of the Gears and the origins of The Garden, he uncovers dark secrets about the world's history and the true nature of the society he once belonged to.

The plot is driven by Rudo's journey of self-discovery, his growing relationships with fellow Gachiakuta members, and the escalating conflict between the two societies. Key characters include Enjin, the enigmatic leader of the Gachiakuta, who harbors a personal vendetta against The Garden; Zanka, a skilled fighter with a tragic past; and Riyou, a former resident of The Garden who becomes Rudo's ally. The series explores themes of social inequality, environmental degradation, and the consequences of unchecked power, all while maintaining a focus on action, mystery, and the evolving dynamics between its characters.