Led by Reinhard von Müsel, the Galactic Empire crushes the Free Planets Alliance in the Fourth Battle of Tiamat. Arriving in the Imperial capital of Odin to a hero's welcome, Reinhard's victory earns him a promotion to High Admiral and the distinguished title of Count von Lohengramm. On the other side, Yang Wen-li safely returns to the Alliance capital of Heinessen without fanfare and reunites with his dear friends. Reinhard and Yang look forward to a long-awaited reprieve. However, at the request of the scheming Duke Otho von Braunschweig, the Imperial High Command orders the new High Admiral to invade the Alliance with a fleet of twenty thousand ships. After the Duke leaks the plan to the Alliance government, three fleets totalling forty thousand ships are sent to counter the incoming attack and recreate the famous Battle of Dagon. But even though Reinhard is outnumbered two to one, he has an ingenious plan—and Yang sees right through it. Will Yang's superiors heed his warning before it is too late?

Four months before Count von Lohengramm of the Galactic Empire faced Yang Wen-li of the Free Planets Alliance at the Battle of Astarte, he was still just Reinhard von Müsel. The youngest admiral in the Empire's history, Reinhard was disdained and dismissed by his peers as the brother of the Kaiser's concubine. Upon arriving at Iserlohn Fortress with his expeditionary fleet, Reinhard immediately receives an order from the ambitious and cunning Fleet Admiral Gregor von Mückenberger: to intercept an Alliance fleet in a neighboring starzone. Despite recognizing this as a veiled attempt to get him killed in combat, Reinhard nevertheless orders his tired and weary men to engage the enemy in the atmosphere of the gas giant Legnica. But unbeknownst to him, this will mark the first of his many historic encounters with the Hero of El Facil.

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.

Despite having the upper hand, BC Freedom High School suffers a thorough defeat at the hands of Ooarai Girls Academy. Following their victory, the Ooarai girls decide to take a break before the next round. After discovering that Momo Kawashima is taking care of her family while studying for the university entrance exams, the rest of the Ooarai team become more determined to win the Winter Continuous Track Cup for the sake of Momo and her family. Meanwhile, the second round of the tournament has started, and Ooarai now has to face Chi-Ha-Tan Academy. Having learned from the first round to not underestimate their enemies, Ooarai slowly approaches their opponent on the thick jungle battlefield. Despite their best attempts to be cautious, Ooarai is immediately put in a difficult situation as Chi-Ha-Tan employs several new strategies devised by Haru Fukuda. Finding themselves between a rock and a hard place, Ooarai must claw their way out to claim another comeback victory and keep their championship hopes alive.