"Sidestory of Gundam Zeta" is a manga that expands on the events of the "Mobile Suit Zeta Gundam" anime, offering additional perspectives and narratives within the Universal Century timeline. The story is set during the Gryps Conflict, a period of intense warfare between the Earth Federation's Titans and the anti-Earth Union Group (AEUG). The manga delves into the lives of secondary characters and explores untold aspects of the conflict, providing a deeper understanding of the broader war.

The narrative focuses on the struggles of pilots and soldiers who operate in the shadow of the main events of "Zeta Gundam." Key characters include members of the AEUG and Titans, as well as civilians caught in the crossfire. The manga highlights the moral ambiguities of war, with characters often questioning their allegiances and the ethical implications of their actions. Themes of sacrifice, loyalty, and the human cost of conflict are central to the story.

One of the primary arcs follows a group of AEUG pilots as they undertake covert missions to disrupt Titan operations. These missions often involve high-stakes battles, espionage, and strategic maneuvering. The manga also explores the internal politics of both factions, revealing the tensions and power struggles within their ranks. Characters grapple with personal losses, the trauma of war, and the challenge of maintaining their humanity in a dehumanizing conflict.

The Titans are portrayed as a ruthless and authoritarian force, employing brutal tactics to maintain control. Their actions often push characters to question the morality of their own side, blurring the lines between right and wrong. The AEUG, while positioned as the resistance, is not depicted as entirely virtuous, with its own flaws and internal conflicts.

The manga introduces new mobile suits and technologies, expanding the mechanical design lore of the "Gundam" universe. Battles are detailed and strategic, emphasizing the tactical aspects of mobile suit warfare. The artwork captures the intensity of combat and the emotional weight of the characters' experiences.

Overall, "Sidestory of Gundam Zeta" serves as a complementary piece to the main "Zeta Gundam" narrative, enriching the Universal Century timeline with additional depth and perspective. It provides a nuanced exploration of the Gryps Conflict, focusing on the personal and collective struggles of those involved in the war.