The 150-year-long stalemate between the two interstellar superpowers, the Galactic Empire and the Free Planets Alliance, comes to an end when a new generation of leaders arises: the idealistic military genius Reinhard von Lohengramm, and the FPA's reserved historian, Yang Wenli. While Reinhard climbs the ranks of the Empire with the aid of his childhood friend, Siegfried Kircheis, he must fight not only the war, but also the remnants of the crumbling Goldenbaum Dynasty in order to free his sister from the Kaiser and unify humanity under one genuine ruler. Meanwhile, on the other side of the galaxy, Yang—a strong supporter of democratic ideals—has to stand firm in his beliefs, despite the struggles of the FPA, and show his pupil, Julian Mintz, that autocracy is not the solution. As ideologies clash amidst the war's many casualties, the two strategic masterminds must ask themselves what the real reason behind their battle is.

Ginga Eiyuu Densetsu Gaiden is the first of two OVA adaptations of side stories from the Ginga Eiyuu Densetsu novel series. This first adaptation follows the achievements of Reinhard von Müsel and Siegfried Kircheis of the Galactic Empire before the fateful Battle of Astarte. The Silver-White Valley Reinhard and Kircheis graduate from their military academy and are immediately sent to the frozen frontier planet Kapche-Lanka. Unbeknownst to them, their new superior schemes to kill Reinhard on behalf of a rival of Reinhard's sister Annerose von Grünewald. Dreams of the Morning, Songs of the Night Reinhard and Kircheis are assigned to the Imperial Military Police, where they uncover the corrupt and oppressive practices of the Empire's law enforcement. They are soon ordered to investigate the murder of a student at their alma mater. Dishonor As Reinhard awaits the bestowal of his new title of Count von Lohengramm, he sends Kircheis to the artificial resort satellite Kreuznach III for a vacation. Restless from the lack of work, Kircheis assists the local police with a drug trafficking case related to an attack on a disgraced former Vice Admiral. A Hundred Billion Stars, a Hundred Billion Lights While Reinhard is still a commodore in charge of only a single squadron, he laments the incompetence of his superiors during a battle against the Free Planets Alliance. Amassing military successes under the direct command of Vice Admiral Richard von Grimmelshausen, Reinhard repeatedly clashes with Hermann von Lüneburg, a commodore and former regimental commander of the Alliance's infamous Rosen Ritter.

Ginga Eiyuu Densetsu Gaiden (1999) is the second of two OVA adaptations of side stories from the Ginga Eiyuu Densetsu novel series. This second adaptation follows the achievements of Yang Wen-li of the Free Planets Alliance before the fateful Battle of Astarte, and continues the tales of Reinhard von Müsel and Siegfried Kircheis of the Galactic Empire. Spiral Labyrinth Yang is propelled to the spotlight after his famous evacuation of civilians from El Facil. Following an unofficial double promotion and a flurry of media attention, he chronicles his research of the Year 730 Mafia—a close-knit group of Alliance military officers centered around the famed tactician Bruce Ashbey. He investigates a startling claim by Ashbey's deceased widow that may have enormous political ramifications: that the great war hero was not killed in action but murdered. The Mutineer Reinhard and Kircheis are posted on the destroyer Hameln II, docked at Iserlohn Fortress. After gaining the respect of the crew, Reinhard's leadership is tested when the captain is severely wounded and passes command authority to Reinhard, the next-highest ranking officer on deck. The Duelist While Reinhard and Kircheis are working in the Imperial capital Odin, Reinhard learns of a mining rights dispute involving Dorothea von Schaffhausen, a friend of his sister Annerose von Grünewald. Upon hearing that Count Herxheimer intends to settle the matter with a duel, Reinhard volunteers to represent the Schaffhausen family. The Retriever After falling out of favor with the nobility, Count Herxheimer is trying to escape to the Free Planets Alliance with a stolen Seffle particle generator prototype. Reinhard is tasked with retrieving both the prototype and the defector, but is only assigned the cruiser Hässliche Entlein due to the confidential nature of the mission. The Third Battle of Tiamat To commemorate the 30th year of the reign of Kaiser Friedrich IV, the Empire announces a large-scale military campaign against the Free Planets Alliance. In the ensuing clash between the Imperial expeditionary force and three Alliance fleets, Reinhard's timely intervention shapes the tides of war.