Chirico recovers after all and join Fyana in another attempt to hold off the enemy. The battle is fierce, but this time Chirico is not up to it. He is hit again, and Fyana pulls him inside as the Balarant Fatties swarm the ship. Their disappearance is reported to the Balarant patrol fleet captain, who orders his men inside to capture their mysterious opponents.

Fyana evades the Fatties as they comb the inside of the ship for her and Chirico. She finds her way to the infirmary for medication, and Battleship X makes a move of its own, firing its engines and moving off in a new direction. While some of the invading Balarant ATs attempt to disable the engines, Fyana returns to Chirico and revives him with the medicine she obtained. He laments his own helplessness, saying that Ypsilon would never fail her...and he slips back into unconsciousness as she prepares to face the approaching enemy. Fyana now fights alone, both on foot and in a Scopedog, pausing only to wonder again who placed her in this situation.

Not far away, the Secret Society follows the battle in their own ship, the Teltain. Captain Futtor keeps watch as Arron and Gurran put Ypsilon through a battery of emotional tests and discuss the prospect of a rematch between him and Chirico. Far ahead, a planet looms in the distance, and Fyana cares for a sleeping Chirico. They have faced much already, but the worst is yet to come.

"I've wandered the depths of hell. Its hot, suffocating depths. And in the distance, a light. Our ship, as though following a beckoning beacon in the night, drew us ever closer to the planet that lay before us."

Zanjeny and his crew debate the continuing situation. Space Battleship X cannot be identified as a Gilgamesh ship, but the Balarant still cannot risk starting an incident in the nonaggression zone. All they can do is wait for their opponent to make the first move. On the ship, Fyana has come to a decision - she will surrender herself to the Balarant in exchange for medical treatment for Chirico. Her attempt to do so is observed by Futtor's men, and just as Fyana seems to have won, the Balarant ship is destroyed by the Teltain.

She makes it back safely to Battleship X, and as the unknown planet looms closer, the Teltain launches another attack. Fyana attempts to radio Ypsilon, begging him to stop the assault, but communication is knocked out before anything can come of it. The ship begins to descent into the atmosphere of the planet, and a platoon of MKII Tortoises is launched against Fyana. Ypsilon joins the attack in his Strikedog, but when he faces off against her directly, his emotions begin to cloud his judgment.

Despite this, he manages to capture her, and as his men haul her away, Teltain launches another barrage of missiles at the descending battleship. Horrified, Fyana tears herself away and plummets to Chirico's aid once again. She dives inside, followed by more Tortoises, but everyone is thrown into chaos when the giant ship finally smashes into the surface of the planet and comes to rest. Just as Fyana is finally cornered, Chirico rushes to her aid in a Scopedog of his own, and fights his way out to the surface of the smoking ship...where Ypsilon awaits. The sun of the unknown planet rises as they level their weapons at each other.

"My strength had returned to me. But, as strong as Ypsilon's murderous rage was, the smell of blood from this planet's past was even stronger."

Arron and Gurran monitor Ypsilon's emotional index from the Teltain. Now that he faces Chirico, his readings have levelled out to those of a proper killing machine. ypsilon and Chirico lunge at each other, and Fyana holds off the Tortoises, admonishing Chirico to rember that they're both fighting to live. He instructs her to get back inside and stand ready in the control room. Carefully, Chirico lures Ypsilon and his troops toward the engines of the crashed ship and leaps off the edge. Ypsilon follows - and Fyana activates the thrusters! Caught in the backblast, Ypsilon's Strikedog is smashed, and the invaders retreat.

Now convinced that a third, more aggressive party has joined the fight in the nonagression zone, Zanjeny and his staff order a task force into the area in support of their patrol fleet. On board Teltain, Ypsilon recovers from his injuries and thinks of his next battle with Chirico.

Knowing Ypsilon will be back, Chirico tampers with the verniers on the now-silent hull of Battleship X and finally realizes what planet he is on: Sunsa, the site of the bloodiest battle of the Hundred Years War...a battle he himself has remembered in nightmares. An AT landing craft appears, and Chirico and Fyana rush to the control room as it lands on the hull. Out steps Ypsilon in another Strikedog, with more Tortoises backing him up. One by one, the verniers blast away at them.

Ypsilon reports this setback to Futtor on the Teltain, who suddenly has to face a problem of his own - Balarant ships approach, and he has no AT platoon to fight them off! Forced to tip his hand, Futtor goes on the offensive, and a devastating battle erupts in space! Having found their way inside Battleship X, Ypsilon and his remaining men reach the empty control room, and discover that Chirico has set the entire ship to self-destruct! They escape just in time, and launch as the vessel rips itself apart.

chirico and Fyana has also gotten away, loading a transport truck with ATs and driving deep into the Sunsa desert. There, others await them...

"Would we ever have any peace? I felt like screaming. If there was a God on this world, he was a cruel one. Too cruel. This planet's name is Sunsa. And I know it holds no welcome for me at all..."

Huge vehicles watch the approaching transport truck and prepare to launch an attack. But they are unprepared for a skilled AT pilot in a Scopedog, who swiftly disables one of their vehicles. The struggle is interrupted by a voice from above; a ship passes overhead and calls out to the AT pilot. An astonished Chirico realizes it is Bouleuse Gotho!

In orbit around Sunsa, the Teltain has escaped its battle with the Balarant, and Futtor makes plans to continue the pursuit of Chirico and Proto-One. Meanwhile, Ypsilon examines data from Battleship X. To his disbelief, Chirico seems to have recovered from his earlier injuries three times faster than any normal human...

Gotho's vessel drifts over Sunsa. Inside, Chirico and Fyana are introduced to their attackers: Zophie and her gang, who salvage weapons from the desert for Gotho to sell off world. They travel to Zophie's fortress, within the airtight ruins of a damaged building. Vanilla and Coconna are there, and react to their arrival with mixed emotions. Vanilla is ecstatic, but Coconna is furious when she sees Fyana for the first time. Chirico says nothing.

Later, Zophie approaches a weeping Coconna, who reveals that as a Red Shoulder, Chirico has always been cold and unemotional. Meanwhile, Gotho berates Chirico for acting this way toward Coconna. Fyana argues for Chirico's sake, but stops herself before she can say too much. The scene is broken by the arrival of Ypsilon and a platoon of Tortoises from the Teltain. Setting up a perimeter around the fortress, they demand that Chirico be surrendered. Gotho prepares to answer with gunfire, but Zophie stops him - Chirico, after all, is one of the Red Shoulder devils who destroyed their planet, and she is more than willing to throw him to the wolves.

Chirico prepares to face Ypsilon alone, refusing even Fyana's help. She begins to wonder if he really is as cold and unfeeling as Gotho said.

"I know best how I should fight. Gotho had called me a war machine. A murder machine. And now so had my beloved Fyana. If I really was a machine, I doubt their words would hurt me as much as they did. But I'm just a man, and my battle is this hell continues...as does my crushed existence."

Before Chirico and Ypsilon can renew their battle, a new force enters the fray: the Balarant! As Balarant spaceships fire on the Teltain in orbit, fighters streak by over Zophie's fortress and bombard it with explosives. Everyone is forced to flee as best they can. Gotho and the others escape into underground tunnels, Chirico and Fyana drive off in a transport, and Ypsilon's unit slips away into the desert.

Fyana feels herself beginning to weaken, the first sign that her last jijirium bath is beginning to wear off. She leans on Chirico, hoping for the best. Later, their truck gets stuck in a sand dune, and when Chirico investigates the area for tools, he comes across a dead Balarant soldier clutching a map which shows the location of a supply base that may have some jijirium. Suddenly, Zophie appears and fires on them, determined to revenge herself on Chirico. He manages to overpower her, and leaves her alive and furious.

That night, as Chirico helps Fyana through her growing unease, Zophie radios their position to a Balarant AT patrol. The two drive frantically away, but their truck is demolished by Zophie, leaving them vulnerable to the Balarant. Reduced only to their Scopedogs, Chirico and Fyana fight back - but she has now weakened even more, and Chirico barely manages to take out the last enemy AT after Fyana's Scopedog is damaged. He steps out of his own AT to get her aid, but Zophie has hijacked one of the Fatties, and destroys Chirico's Scopedog! Now on foot, he evades her as best he can, but she finally gets the drop on him. A blast rings out...and Zophie's AT explodes! Fyana has managed one more shot, but now her strength fails her completely and she collapses.

Chirico has no choice but to travel on foot to the Balarant supply station, carrying Fyana on his back as their air supply dwindles. Zophie keeps pace, her fury driving her past the point of self-preservation. Content to let her follow, Chirico begins a long march across the burning Sunsa desert...

As Chirico and his friends go to work patching up derelict vehicles, a familiar face looks down on Sunsa from orbit: Rochina. Now in command of a Leslion-class Balarant Battleship, he has crossed both the nonagresssion zone and his allegiance to Melkia in order to find Chirico again. Rochina's ship descend on the abandoned supply station, and Chirico's group is quickly overwhelmed and taken captive. Chirico is taken directly to Rochina, who offers the release of his friends if Chirico will consent to face Ypsilon again. Chirico questions Rochina about who he really is. Rochina's only answer is that he is a man from the kingdom of heaven.

Captain Futtor discusses the situation with Arron and Gurran aboard the Teltain. They have not heard from Ypsilon since the raid on Zophie's fortress, but they are sure he will go after Chirico despite the Balarant presence. When that happens, the Secret Society must be ready to recover him.

Chirico agrees to Rochina's terms, and is freed to prepare for the battle. He doesn't have long to wait - Ypsilon and his small platoon launch an attack on the Balarant landing party and fight their way quickly inside the perimeter. Rochina orders all ships to launch, and Chirico is left behind in a Fatty to face his enemy. In short order, they find each other in an empty chamber deep inside the supply station. Once again, they draw their weapons and prepare to engage. Rochina arrives to watch with Fyana in tow, but there is nothing that can be done to stop the fight now.

"His will to fight was practically a madness. But, as opposed to him, my heart didn't burn. the thing that drove me on was an almost pitiful craving for battle that raged within me."

Chirico and Ypsilon unleash heavy fire, with Ypsilon pausing only to eliminate anyone who threatens to interfere in their battle. Suddenly the entire room starts to shake, and the floor drops out from under their ATs - their battle has ignited the ammo dump! Plummeting helplessly, they disappear into a deep shaft, and Rochina managed to escape with Fyana as the entire building crumbles.

Landing relatively intact, Chirico gets the upper hand against Ypsilon, but does not choose to kill his foe. Instead, he begins to dig himself out and suggests they work together to survive.

On the surface, Rochina orders his men to begin an excavation and recover Chirico. He discusses the situation with Fyana, who suspects that he is hiding the answer to a key question: how has Chirico, an ordinary human, lasted so long against Ypsilon, a Perfect Soldier?

Similar questions burn through Ypsilon's mind as he and Chirico make their way toward the surface. The PS angrily declares himself a superior being, and that he belongs with Proto-One. Chirico corrects him on the name, and Ypsilon demands to know why he calls her Fyana - a question Chirico is unable to answer. Finally, when they reach the upper limits of the shaft, Ypsilon admits that they are alike in one respect; Chirico can fight as well as he can...but Ypsilon will eventually kill him.

On that note, the Balarant excavation team finally breaks through from above and rescues Chirico. Ypsilon slips away just in time to join up with a rescue team from the Teltain, and they fight their way free. Chirico is taken to Rochina, who demands that he be ready to fight Ypsilon again. In return, Rochina orders Gotho, Vanilla, and Coconna flown out of danger.

"It seemed Rochina had kept his promise. My final battle with Ypsilon. The time was fast approaching. Will I survive it, or will he? And if I do survive, what then?"

On the Teltain, Futtor insists that they must leave Sunsa now that Ypsilon has been recovered. Arron and Gurran reply that their mission take precedent. Ypsilon must be allowed to fight Chirico again, and they must stay to observe.

On Rochina's ship, Chirico fine-tunes a Scopedog and writes himself a new mission disc containing everything he knows about the maneuvers of a PS. Fyana speaks with Chirico, admitting she is afraid for him, but he counsels her to accept what must happen. Ypsilon is fighting out of loneliness, and will not stop until one of the tem is dead. Ypsilon, meanwhile, renews himself with a jijirium bath and launches for the surface in a new Strikedog.

On the other side of the galaxy, Melkian General Karmeny meets with Battentain to discuss the implications of what has happened in the Nonaggression Zone. Battentain is shocked to learn of Rochina's defection, and admits he never quite knew how to read the man. Despite the risk to the peace treaty, a task force of Gilgamesh battleships must be sent to Sunsa with Rochina as their target.

Chirico crosses the Sunsa desert to Siguray Crater, where Ypsilon's empty landing craft stands waiting. Chirico takes the bait, and the battle is joined! This time there are no distractions; the two clash with each other time and again. Chirico's mission disc works perfectly, allowing him to match Ypsilon move for move. Rochina takes notice and finally announces to Fyana what he has suspected all along: that Chirico is a true Perfect Soldier! And at long last, Chrico fires the fatal shot that takes Ypsilon down!

Before he can finish Ypsilon off, however, Chirico is interrupted by Fyana, who gives him the shock of his life - that he is more than human. Chirico insists that his mission disc is what allowed him to win, but then notices that the disc burned itself out only a few minutes into the fight. From then on, it was his own ability. Ypsilon insists in his final moments that Chirico has to be a PS...Ypsilon's pride would not allow him to die at the hands of a normal man.

Later, Chirico prepares to leave Sunsa, Rochina's words echoing through his mind: "You are a PS. You want proof? Then go to planet Quent. There you will learn everything."

"What was it that lay hidden in my past? I'd fought Ypsilon and won. But I couldn't believe it. There was no way I could be a PS. The Planet Quent...what awaited me there?"