Mikazuki and Orga's bond is the show's center, and it will wreck you when it matters most. The series doesn't build toward a triumphant ending, it builds toward the cost of loyalty, what happens when two kids with nothing decide to protect each other at any price. By the final episode, you understand that this was never a story about winning a war.

Three hundred years after the Calamity War, Mars depends heavily on Earth's economy, and the military organization Gjallarhorn keeps the peace. Kudelia Aina Bernstein, a young aristocrat from the Chryse region, joins the Martian independence movement and hires the security company CGS to escort her to Earth for negotiations. Guarding her falls to the Third Army Division, child soldiers including Mikazuki Augus and Orga Itsuka. When Gjallarhorn attacks CGS to eliminate Kudelia, Orga sees a chance to rebel against CGS and seize control. To hold off the attackers, Mikazuki takes the controls of the Gundam Barbatos, an old mobile suit from the Calamity War powered by a nuclear reactor. The result is a mecha drama about children fighting to decide their own fate.