"Gundam Reconguista in G" is set in the Regild Century (R.C.), a distant future where humanity has rebuilt civilization after the devastation of the Universal Century. The story centers on Bellri Zenam, a young cadet of the Capital Guard, a military force protecting the orbital elevator known as the Capital Tower. The tower is a vital structure that supplies energy to Earth and space colonies, maintaining a fragile balance between the two. The narrative begins when Bellri encounters Aida Surugan, a member of the Amerian Army, who is piloting a mysterious mobile suit called the G-Self. This encounter sets off a chain of events that disrupts the peace between Earth and space factions.

The G-Self, a highly advanced mobile suit, becomes a focal point of conflict as various groups vie for control over its technology. Bellri, initially tasked with protecting the Capital Tower, finds himself drawn into a larger struggle involving the Amerian Army, the Capital Guard, and the space-based religious organization known as the Towasanga. As the story progresses, Bellri and Aida form an uneasy alliance, navigating the complexities of war, politics, and personal loyalties. Their journey reveals deeper truths about the world, including the existence of the "Reconguista," a plan to reunite Earth and space under a single governance.

Key characters include Bellri Zenam, whose idealism and sense of duty drive much of the narrative; Aida Surugan, whose motivations are tied to her family's legacy and the secrets of the G-Self; and Klim Nick, a rival pilot from the Capital Guard who becomes both an adversary and an ally. Other significant figures include Raraiya Monday, a mysterious girl with ties to the Towasanga, and Mask, a charismatic leader of the pirate faction who plays a pivotal role in the conflict. The series explores themes of reconciliation, the consequences of technological advancement, and the cyclical nature of history, all while maintaining a focus on the personal struggles of its characters.

The plot unfolds through a series of battles, political maneuvers, and revelations about the true nature of the Regild Century. The story's pacing and structure reflect the chaotic and multifaceted nature of the conflict, with alliances shifting and new threats emerging as the characters uncover the deeper layers of the world's history. "Gundam Reconguista in G" presents a complex narrative that intertwines personal growth, ideological clashes, and the broader implications of humanity's relationship with technology and the environment.