The Free Planets Alliance attempted a large-scale offensive within the Galactic Empire, but with a reversal strategy by Reinhard and the Galactic Imperial Navy, they lost three space fleets. Although the 13th Fleet, led by Yang, maintained 90% strength, the other fleets suffered heavy damage. But Lobos, the commander-in-chief, ordered all remaining forces to gather at the Amritsar Starzone, so Reinhard also ordered all of his forces to head there. Yet another battle between the two armies was about to unfold.

Emperor Friedrich IV of the Galactic Empire has suddenly passed away without naming a successor. Edwin Josef, the son of the late prince and the emperor's only surviving direct descendant, is only five years old. The Braunschweig and Littenheim families, into which the emperor's daughters had married, begin scheming to install their respective daughters as the new empress. Thus begins the battle for the throne between the families who serve as guardians to the emperor's three grandchildren. Reinhard has not sided with any of them yet, so a certain influential power seeks to take advantage of his military strength.

When the Free Planets Alliance Navy conquered Iserlohn Fortress, they took two million Imperial soldiers as war prisoners. And during the Battle of Amritsar, the Galactic Imperial Navy took two million Alliance soldiers as war prisoners. A deal has been reached to exchange all of these prisoners at Iserlohn Fortress. Representing the Alliance at the exchange is Yang, the commander of Iserlohn Fortress. Representing the Empire in place of Reinhard, the one who proposed the exchange, is Kircheis. The two men, who have fought one another with equal resourcefulness in battle, meet face-to-face for the first time at the prisoner exchange ceremony.

Animosity continues to grow between Reinhard and Lichtenlade, the guardians of the young emperor Erwin, and the pure-blooded noble families with Braunschweig and Littenheim at their center. In the midst of all this, Hilda, the only daughter of Count Mariendorf, visits the Fleet Admiral's Mansion on Odin to meet with Reinhard. When he asks what brought on the sudden visit, she tells him that the Mariendorf household would like to side with Reinhard in the civil war that could break out at any moment.

Only a short time has passed since the Alliance's failed invasion of the Empire, and an assassination attempt on Admiral Cubersly, a key figure in the Alliance Navy, further deepens the people's anxiety. On top of that, an accidental explosion the following day takes fourteen young soldiers' lives. Growing discontent has caused revolts to break out on several planets within the Alliance. Bewcock orders Yang to put down these revolts, but before Yang has a chance to deploy, a coup d'état is executed on the capital planet Heinessen.

The Lippstadt Nobles Coalition devises a plan to lure Reinhard's forces away from the Imperial capital, Odin, and capture the emperor while Imperial defenses are spread thin. While the nobles fight among themselves over who gets to lead this strike, the Mittermeyer Fleet lays a minefield that forces the rebels off-course, and then strikes them from behind. The defeated rebels flee to Rentenberg Fortress. Reinhard sends Reuenthal and Mittermeyer to occupy the fortress, but upon arriving, they are forced into close-quarters combat with the notoriously barbaric High Admiral Ovlesser.

After easily putting down a revolt on the planet Shampool, Yang is approached by Commander Baghdash, a Department of Intelligence official. Baghdash informs Yang that the 11th Fleet has joined the coup d'état and is headed his way. While the Yang Fleet and the 11th Fleet engage in the Battle of the Doria Starzone, the coup d'état faction remains steadfast, intervening with military force at a peaceful protest on the capital planet Heinessen.

After easily putting down a revolt on the planet Shampool, Yang is approached by Commander Baghdash, a Department of Intelligence official. Baghdash informs Yang that the 11th Fleet has joined the coup d'état and is headed his way. While the Yang Fleet and the 11th Fleet engage in the Battle of the Doria Starzone, the coup d'état faction remains steadfast, intervening with military force at a peaceful protest on the capital planet Heinessen.

After defeating Legrange at the Doria Starzone, Yang's fleet heads to the capital planet Heinessen, which has been taken over by the National Salvation Military Council. Though the council's chairman, Greenhill, understands the severity of the situation, he still believes there's no way Yang's fleet can even penetrate Heinessen's gravitational field because of its specialized defense system, Artemis's Necklace. But Yang had a plan to disable Artemis's Necklace...

Kircheis returns to Reinhard after subjugating a frontier starzone. He wastes no time in asking Reinhard if there's truth in the rumor that he knew of the plans for the nuclear attack on Westerland, but let it happen anyway. With the final battle against the coalition of nobles looming before them, the pair's relationship begins to take a turn like none they have experienced before. Meanwhile, the Lippstadt Nobles Coalition, which had barricaded itself in Geiersburg Fortress, prepares to launch all of its forces in the final battle against Reinhard.

The battle against the Lippstadt Nobles Coalition has ended, and a victory celebration and audience with the war prisoners is being held at Geiersburg Fortress. The guards forbid Kircheis from carrying his firearm inside, even though he always had permission to keep his weapons in Reinhard's presence before. As the war prisoners face Reinhard one by one, Braunschweig's adjutant, Ansbach, enters with his leader's body in a coffin...

With their respective conflicts handily wrapped up, both Yang and Reinhard spend their time in the afterglow counting their regrets.

The head of the Galactic Empire's Science and Technology Department, Anton Hilmer von Schaft, is a man known for his sheer ambition. He is now presenting to Reinhard a large-scale plan to retake the long-lost Iserlohn Fortress.

The planet Fezzan is an autonomous dominion located in one of the only two safely navigable zones that connect the Galactic Empire and the Free Planets Alliance. Every Fezzani head of state, or Landesherr, has protected the independence of the dominion by maintaining strong ties with both its much more powerful neighbors. However, the current fifth Landesherr, Adrian Rubinsky, also known as the Black Fox of Fezzan, seems intentioned to change this long-standing policy.

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 Empire moves forward with its experiments to warp Geiersburg Fortress through space to attack Iserlohn Fortress. Reinhard and several of his subordinates watch anxiously from the safety of his flagship as the countdown begins. Amidst the tension, some of Reinhard's most trusted men discuss how he has changed since Kircheis died a year ago.

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.

As if to fill the void caused by the death of Siegfried Kircheis, Reinhard von Lohengramm devotes his energies entirely on reforming the Galactic Empire. His wide-ranging reforms earn him tremendous goodwill from the populace, and despite considering them to be publicity stunts, even his sceptics are suitably impressed by the breadth of the reforms.

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.

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 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.

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