Season 1

In humanity's distant future, two interstellar states—the monarchic Galactic Empire and the democratic Free Planets Alliance—are embroiled in a never-ending war. The story focuses on the exploits of rivals Reinhard von Müsel and Yang Wen Li as they rise to power and fame in the Galactic Empire and the Free Planets Alliance.

The Free Planets Alliance counters the Galactic Imperial Navy's advance in the Astarte Starzone, still divided into the 2nd, 4th, and 6th Fleets to surround the latter on three sides. The Alliance top brass are certain that their victory is assured, but 2nd Fleet Deputy Staff Officer Commodore Yang predicts the enemy's attack on their divided forces before their encirclement is complete.

Annerose, Reinhard's older sister, lives in the palace as the kaiser's favorite mistress. As Reinhard and Kircheis make their way to her residence for a visit, they both recall memories of their childhood together. Then Annerose, after greeting them with a smile that hasn't changed since they were young, asks Kircheis to continue looking out for her brother and guide him back toward the right path if he ever goes astray.

Until the age of 16, Yang Wen-li spent most of his life on an interplanatary merchant spaceship with his father, who was a trader. After his father's death, Yang entered the Free Planets Fleet Academy to study war history. There, he met Jean, who would become his best friend, and his childhood friend Jessica, a music school student

After its defeat at the Battle of Astarte, the Free Planets Alliance Navy returns to the planet Heinessen, the Alliance's capital. A memorial service is being held for the 1,500,000 Alliance soldiers who died in the battle, but according to Rear Admiral Cazerne, it's nothing but a political show put on by National Defense Committee Chairman Trunicht. Yang reluctantly attends the service, but while there, he encounters an old acquaintance he never expected to see

Sub-lieutenant Greenhill, a woman with an unusually keen memory, is added to the crew of the 13th Fleet along with several other highly well-regarded officers. Captain Schönkopf and some members of his regiment, the Rosen Ritter, board a previously captured Imperial cruiser as part of Yang's plan to infiltrate and capture Iserlohn Fortress, disguising themselves as Imperial soldiers being pursued by the Alliance

Schönkopf and his subordinates from the Rosen Ritter successfully infiltrate Iserlohn Fortress by disguising themselves as Imperial soldiers on the run from the Alliance. He requests an audience with the fortress's commander, saying he wants to relay some vital information acquired during an espionage mission. The commander, Admiral Stockhausen, gives permission, but the captain of the control room guard grows suspicious.

Kircheis suppresses the Castrop Rebellion in only two days of combat, earning a promotion to vice admiral. Meanwhile, Captain Oberstein, having abandoned the commanders at Iserlohn to flee on his own, seeks an audience with Reinhard. Despite Kircheis's misgivings, Reinhard recognizes Obersteins talent as a tactician and takes him on as a subordinate.

A High Council vote determines that the Free Planets Alliance will invade the Galactic Empire. Meanwhile Yang, after having his resignation rejected by Chief Sithole, visits a restaurant with Julian for dinner and runs in to Frederica Greenhill, who was there with her father. The four of them dine together. On the way home afterward, Yang learns that Jessica, the fiancée of his fallen comrade Lapp, has decided to go into politics.

A meeting is underway at the Free Planets Alliance Navy Integrated Tactical Operations Center to plan the Alliance's large-scale invasion into Imperial territory. Commodore Falk, an operations staff officer, proposes a plan, but Vice Admirals Bewcock and Yang raise concerns about the dangers of invading with widely separated forces and an excessively long supply line. Meanwhile, Reinhard is concocting a plan to draw the Alliance Navy deep into Imperial territory and destroy them in one fell swoop.

The Free Planets Alliance Navy Expeditionary Fleet encounters a grave shortage of food during its advance into Imperial territory. The 5th Fleet commander, Admiral Bewcock, conveys Yang's proposed escape plan to Supreme Commander Lobos, but Lobos fails to comprehend the situation and won't allow them to flee. Meanwhile, Reinhard has already given orders to Kircheis to strike the Alliance Navy's supply convoy. The Imperial Navy's counterattack has begun!

The Free Planets Alliance Navy Expeditionary Fleet is fighting a severe supply shortage, and the supply convoy that was sent to save them has been destroyed by Kircheis in a fierce attack. Without their desperately needed supplies, the disheartened Alliance fleet takes a hard hit from the Imperial Navy. As Reinhard's subordinates take out the Alliance fleets one by one, Yang's 13th Fleet is attacked by the Kempff Fleet.