The Emperor of Mars calls for a cease fire. Inaho and friends take the moment to rest aboard an Earth Navy Ship. Slaine tries to find a way to reveal the conspiracy of the Martian Forces true intentions. 
5 years before the Second Earth-Mars War, in 2009, a rocket crashed into a castle within the Vers Empire. The craft opens, and Slaine Troyard steps out in a spacesuit, pulling off his helmet.
Water gushes out of his spacesuit, and he also chokes out water. As he hangs out, harnessed to the inside of the rocket, Princess Asseylum Vers Allusia walks up to him. Slaine falls unconscious, so the Princess tries to suck the water out of his body by giving him mouth to mouth. As Slaine is revived, he lays his eyes on the beautiful girl.
Back in 2014, on the planet Mars. Emperor Rayregalia Vers Rayvers learns of the assassination of his granddaughter from a Vers Knight. Unlike the Orbital Knights, the Emperor has no agenda. When told it was a terrorist act, he says that it does not imply hostile intent from United Earth.
But the knight believes the security was deliberately lax in allowing Anti-Vers factions on Earth to carry out their terrorist act. Plus, the possibility of the assassination being perpetrated by the UE government under the guise of a terrorist attack. The Emperor is baffled and thus orders the knight to inform the UE government that they are suspending hostilities and to uncover the truth.
Count Saazbaum congratulates his fellow Orbital Knight but he then asks where Sir Trillram is, believing he is still out distinguishing himself on the battlefield.
Count Cruhteo regrets to inform Count Saazbaum that he has fallen in battle, caught in a meteor bombardment that "some ruffian" launched on his territory. Count Saazbaum finds this odd as he informed Sir Trillram of the bombardment. Count Saazbaum asks Count Cruhteo if anyone witnesses Sir Trillram's end.
Slaine sees Vlad and his Argyre return from his battle with the KG-6 Sleipnir. Slaine wonders what he should do, knowing that the Orbital Knights knew that Princess Asseylum was alive. If he does nothing, she really is assassinated sooner or later. An Angry Vlad demands that his Argyre be repaired immediately. Slaine sees the damage done to the Argyre's head and runs to Vlad, glad to know that he is unharmed, but he begs to differ as his honor has been tarnished.
Slaine asks if his opponent was powerful, but Vlad replied that he was simply made a fool of some "orange, impudent cur". Vlad asks Slaine why he is there and not at the Count's side. Slaine explains that he was disciplined for speaking out of turn, wishing that Count Cruhteo would send him into battle. Vlad says he is just like the other "Terrans", impudent and eager to distinguish himself in battle and win favor, but Slaine says that he just wants to avenge Princess Asseylum.
On the bridge of the UES Wadatsumi, United Earth Navy personnel teach Nina about the ship's autopilot feature. Nina wonders if they, being students, would be sent into battle or not. Shigo just says these are supplementary lessons, just to cover their bases.
Captain Darzana Magbaredge congratulates Inko Amifumi for her efforts in stopping the enemy Kataphrakt, but Inko points out it was Inaho Kaizuka who planned the operation. Captain Magbaredge inquires on what Inko meant by "operation". Inaho shows modesty by saying that it was not elaborate enough to call it an "operation".
Inaho and Inko are congratulated for saving the lives of Captain Magbaredge's crew and many civilians. Captain Magbarege says that if they were enlisted, she'd be tempted to put them in for commendations; medals, as XO Mizusaki explains. Inko is delighted that they could get medals if they were to join the UFE officially. She says she has never seen anyone with a medal. This is because nobody's seen any real fighting for so long, as Lt. Marito interjects. Lt. Marito corrects Inko calling him "Instructor Marito" as they are not in school.
Inaho salutes Lt. Marito as he explains that honor is about the only reward they can hand out in a war. Dr. Soma Yagarai suddenly appears and asks for Lt. Marito for a medical checkup. He suspects Lt. Marito was drunk, but he sees that his flask of alcohol is still full. Lt. Marito's influence comes from elsewhere and remembers the Kataphrakt he encountered at Tanegashima. Lt. Marito pulls out a dog tag with the name "John Humeray" on it.
Dr. Yagarai believes that Lt. Mario's hands are clean because he saved Humeray's life. Suddenly, several soldiers run past Dr. Yagarai's office, they say the Vers have announced an armistice. Calm and Inko watch the fuzzy broadcast with the refugees. Seylum deduces that her grandfather must be trying to put a stop to the knights' outrageous behavior. Count Cruhteo is outraged that the Emperor has issued an armistice without any word to the Orbital Knights.With his plans thwarted he believes he may be able to counsel the Emperor, Slaine stands eagerly. Count Saazbaum is shown footage of the wreckage of the Nilokeras and learns that Sir Trillram was not killed in the meteor bombardment and so he issues an order to investigate Castle Cruhteo.
Count Cruhteo places his hand upon a device in the audience chamber of his Landing Castle.
Yuki complains about how the Vers open hostilities just as they end them abruptly; Shigo suggests the enemy isn't monolithic. XO Mizusaki asks if anyone has contacted them yet, but the jamming is still too strong. Seylum makes her way through the ship to speak to Captain Magbaredge so she can reveal her identity.
Eddelrittuo panics and accidentally calls her Princess. Seylum wants the Captain to inform Vers of her safety, believing it will end the war. Still, Eddelrittuo thinks it's too dangerous because the rebels will come for her before word reaches the Emperor. Seylum believes the armistice provides them with the perfect opportunity. Rayet suddenly appears and says not to underestimate the rebel, for they aren't the sort to obey the terms of an armistice.
Rayet demands she be left out of their plan. Breaking the armistice, a Sky Carrier drops the Argyre onto the Wadatsumi; Vlad won't have the war end without him having a chance to redeem his honor. Lt. Marito runs out of the mess hall. XO Mizusaki orders Kataphrakts to launch and suggests relocating to the CIC, but the Captain is fine.
Count Cruhteo and the Orbital Knights' plans have been thwarted by the Emperor's armistice even though his own flesh and blood was "killed". Coming out of the audience chamber, Count Cruhteo tells his men to uncover the details of the Princess's assassination per the Emperor's orders. Slaine listens to their plans closely behind the corner. Slaine heads into the audience chamber to speak to the Emperor, placing his hand on the device. The holographic technology from Aldnoah makes it look like he is back on Mars.
Vlad is bent on vengeance and challenges the Wadatsumi crew to pick up where they left off. The Argyre draws its beam Katana and destroys several of the Wadatsumi's gun turrets. The Aldaniti Platoon of KG-7 Areions deploy on the elevator for combat.
All units are warned to use AP rounds instead of HE rounds. Lt. Marito also makes his way to battle in his KG-7, but he backs out as he as thoughts about Tanegashima.
Although the KG-7's projectiles are now unaffected by the Argyre's application of the Leidenfrost effect, the Argyre can still use its beam katana to deflect them. Meanwhile, Slaine runs into the holographic palace to find the Emperor.
The Argyre picks up a turret with its beam Katana and throws it at the platoon, the distracting enables it to destroy one KG-7. The Argyre heads behind the bridge of the Wadatsumi to use it as a shield. Inaho goes to his KG-6 Sleipnir despite protests from his sister. Before deploying, he asks his sister for his pajamas, the one with the patches.
The Argyre draws out a second Katana and slices two KG-7s at once. Slaine enters the Emperor's bedroom, they have met before. He informs the Emperor of the truth, that Princess Asseylum is alive and that it was the Orbital Knights who made an attempt on her life in their lust for war with Earth.
Vlad proceeds to resume the fight with his nemesis, Inaho. Inaho has equipped his KG-6 with a tactical suit, Vlad laughs as he firmly believes that there is no armor his blades cannot slice through.
The KG-6 is locked in combat with the Argyre; his classmates and the refugees cheer him on as they watch the battle on screen from the mess hall. Rayet explains that the KG-6 has reactive armor. Calm is amazed as Inaho has used the blasts to disperse the blade's plasma.
Inaho pulls both arms of the Argyre and asks the bridge to tilt the ship; XO Mizusaki orders the flood ballast to open well dock hatch; water flows into the ballasts to thrust the ship.
The KG-6 slips down the ship, dragging the Argyre with it. Inaho immediately deploys his airbags and ejects from the KG-6 Sleipnir, leaving both Kataphrakts to fall into the water. The plasma, reactive armor, and water cause a vast steam explosion destroying the KG-6, Argyre, and Vlad. Inaho descends safely in his cockpit with three parachutes. Captain Magbaredge rhetorically asks XO Mizusaki that Inaho isn't an average student.
Rayet Areash arrives in a speedboat to pick up Inaho. She gives him her hand; he smiles. Lt. Marito stresses how he backed out of the battle, he clenches his fist, holding John Humeray's dog tag and bangs the wall of the ship.
Slaine begs Emperor Rayregalia to stop the war without delay and to save Princess Asseylum. Slaine finishes his plead to the Emperor and turns off the Audience Chamber he is using. Count Saazbaum's hologram suddenly appears in the Emperor's bedroom. He has gotten to the Emperor before Slaine has and passes off Slaine's message to the Emperor as scandalous behavior to deceive him with lies. Count Saazbaum urges the Emperor to smite the Earth with the iron first of justice. Emperor Rayregalia officially ends the armistice.Later, Count Saazbaum appears in the audience chamber of his own castle. He knows that Slaine Troyard means to harm their cause.
|2||Asseylum Vers Allusia|
|3||Rayregalia Vers Rayvers|
|“||Sins you've committed cling to your soul and haunt you forever. And sins that have gone unpunished aren’t forgiven until you die.||”|
—Lt. Koichiro Marito
|“|| Attention, foolish people of Earth.
Raygalia Vers Rayvers, noble emperor of the Vers Empire, has issued an armistice declaration to the United Earth government.
Even as we feel intense shame in our common ancestry with you, our desire is that this act conveys to you, the deeply sinful people of Earth who took the life of Her Highness, Princes Asseylum, the profound compassion of His Imperial Majesty Raygalia. I repeat, Rayregalia Vers Ravers, noble emperor of the Vers Empire…
|“||Reactive armor. Armor plates that are made with of explosives. They were originally designed to detonate and deflect incoming enemy fire.||”|
|“||Steam explosion. The massive amount of thermal energy in those blades flashed the seawater to steam and the impact from the high pressure steam destroyed him.||”|
—Inaho Kaizuka as he descends
|“|| Captain Magbaredge: Inaho Kaizuka… He hardly seems like a student, does he?
XO Mizusaki: No, ma’am. He’s a surprisingly useful boy
Captain Magbaredge: Mizusaki, Shall I tell you why you can’t get a date?
XO Mizusaki: Don’t partners prefer a forthright personality?
Captain Magbaredge: Yours isn’t forthright. It’s unfiltered.
|“|| In the name of Rayregalia Vers Rayvers, Emperor of Vers, I hereby renew my declaration of war.
Attack the Earth!
Those who would do harm to my flesh and blood…
—Emperor Rayregalia Vers Rayvers ends the armistice.
- When Inaho's mecha was damaged, an error resembling that from an Emacs bug report shows up on one of the screens.