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.

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

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.

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.

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...