Over a hundred years ago, humanity suddenly found itself faced with a new predator. They were far more powerful than humans. Humanity was immediately pushed to the brink of extinction.

The survivors built 3 walls:
Maria
Rose
Sina

There, they enjoyed a century of peace. 

But nothing lasts forever...

*opening starts*

As afternoon struck, hole is not fixed and Titans are scampering around the Trost.

One reason so many soldiers died in the Titans' attack on Trost was the absence of the elites in the Survey Corps

Only that morning, they had embarked on a reconnaissance mission beyond the walls.

A few hours ago

Civilian: They're here! The main force of the Survey Corps!

Civilian: Commander Erwin, kill the Titans for us!

This is at the point of time of where Eren and the cadets seen the Survey Corps main unit.

Civilian: Look, it's Captain Levi! They say he's as strong as an entire brigade.

Levi: Tsk. Spare me.

Hange: If they knew how fussy you are, they wouldn't look at you with such admiration.

Levi just scoffs about it and the gates are opening, Hange is hyper to see the Titans again outside.

Hange: Lo, the threshold of Titania! Can't you just envision the horrors in store for us, comrades? I'm on pins and needles! We bag an Abnormal or the other one, I'll burst with tears of joy!

Hange is still stuck inside her head about the 00 Core Gundam. She can't forget it's different looks, sizes and capabilities.

Levi: I think we've bagged the craziest abnormal already.

Hange: What? Seriously? Where?

Levi: *holds the ponytail and turns her face to his glaring looking one* I meant, you.

Erwin: Move out!

 Outside of the walls

The Survey Corp's primary purpose is to establish bases of expansion. Acting  as a spearhead for human knowledge. Theirs is a solemn and dangerous honor. Thanks to the ingenuity of its exemplary members, the regiment's survival rates have improved. 

That said, excursions into long-relinquished territory still commonly result in a death-toll exceeding 30%. A stark illustration of the disparity between our own strength and that of the Titans. 

A titan got one of the soldiers biting him playfully.

Soldier: One day... One day you'll all just be a bad memory. Mankind will destroy all of you! Mark my words: the last ones standing will be us!

He stabbed it's face with his broken blade, but it barely did any damage at all, and literally bit it's lower part.

Soldier: Gorge while you can, you bastard...! Just wait 'til Captain Levi-

And then a grapple hook came grazing the Titans nap and it was Levi who immediately killed the Titan who's holding the soldier. Levi then observes the targets.

Levi: 'One on the right. Two on the left'

Just then a voice of a woman named Petra Ral, behind her was Gunther and Eld, Levi squad members has arrived.

Petra: Captain! The reinforcements are here, sir!

Levi: Good. Tend to our comrade below, Petra. *turns to Gunther and Eld* You two, take out the Titan to your right. The pair on the left belongs to me.

Petra: What? Captain, wait!

They moved out, two scouts dodged the pure Titans lunge.

Hange: Yaahoo!!

Meanwhile, Hange is just riding on it like a bull rider. She lands on the front of the Titan and started acting as a gentle tamer.

Hange: It's okay! I won't hurt you. 

Then the Titan uses its left hand to grab her but missed as Hange evaded it with her gear.

Hange: So close! My turn!

She cross slash the Titan making it screamed in death and lands back to the ground.

Hange: There you go. See? *blood dissipates* That didn't hurt at all, did it?

Meanwhile, Levi will take out the two Titans on the left just like he said as he lands on a roof of a abandoned house.

Levi: You all have the stupidest expressions.

He evades the incoming bite by attaching the grappling hook on the other side and flies behind it and killed in the process. He goes to the next one and throws the blades at its eyes making it scream in pain.

Levi: Whoa... *balances* Stay put. Otherwise, it'll get messy when I slice you. 

He unsheathes fresh blades from the magazine as he jumps and spins behind the titan, slicing its nape in the process and killing it. He goes back to the roof and looked at its hands and it has blood of the Titan on it.

Levi: Tch. You're blood is as filthy as your mouth is.

He gets his handkerchief and drops back to the ground and make its way to a soldier who's bitten by the Titan mere moments ago.

Petra: Captain, the bleeding won't stop...

Soldier: *weakly* Captain...

Levi gets close and talks to him.

Levi: What is it?

Soldier: W-Was I able... to help humanity? Or will I die, never having been of any use at all?

Levi reminded himself of this a way back. 

Levi: *grabs its hand* You have done a great deal. And you will continue to do so. The resolve you leave behind will give me strength.  I promise you... I will obliterate the Titans!

The Soldier heard it before he loss his life from the excessive bleeding.

Petra: Captain... *tears* He's gone.

Levi: Did he hear me to the very end?

Petra: Yes. I'm sure he did. Look. 

They see it's soldier's face has tears, meaning he heard it and Levi will definitely mean it's words.

Petra: He seems so at peace...

Levi: Very well then.

But then, they heard a horse galloping close to them. They saw Erwin and its men riding their horses.

Erwin: Levi! We're pulling back.

Petra: Eh?

Levi: Pulling back? We have yet to push ourselves to the limit. Are my men dying for nothing?

Erwin: The Titans are heading north, towards the town.

They're shocked by this, and they know what it means.

Erwin: Just like 5 years ago... something is happening in town. The wall may have fallen.

They're gritting or gripping their teeth and blades. But then Erwin said another thing that makes them surprised by this revalation.

Erwin: Also, we just saw something fly above us fast a few moments ago.

Levi: What is it, now?

Erwin: Familiar with the blue colors emitting from the legs?

Levi: Blue? You don't mean...

Petra: What is it, commander?

Erwin: *sighs* It's back. The Mechanical Titan has returned.

Flashback

Real World (2021)

1 year after the Alus vs GBN battle, Y/n is with his brother, Kyoya Kujo. They're buying a Gunpla for Y/n with Karuna and Emilia. They visited the store, and the cashier began to scream at the waiters and waitress. 

Cashier: *happily* Everyone, we have our 250th customer for our Gundam Cafe and Store shop. Let's give him a prize and a round of applause also for our champ is here and the Avalon team!

All of the staff members of this store are gathered in the tables and gives them a round of applause.

And then a certain yet familiar waitress gets close to Y/n as she's smiling at him.

???: Congratulations!! Here's your prize!

She then hands out a SGC 1/200 00 Gundam. Then another familiar yet not waitress comes to see them.

???: Thanks for coming here again, Emilia.

Emilia: Anytime, Yang.

???: Never expected you to be here with your elite members, Kujo.

Kujo: Oh... *scratches* It's just my little brother, is first time here. 

Yang: So, who's the cute one.

Y/n blushes on this and just said his name.

Y/n: *blushes* I-I'm... Y/n... Kyoya Y/n...

Yang: Come here. *embraces Y/n with his head sticking to her chest* Welcome to our GBN base facility.

Y/n is getting suffocated already as his face starts to turn blue.

Karuna: Alright, Yang. You can let go of him now. He's suffocating and also shy.

Yang: *lets go and pouts* Hmph. Party pooper, no fair.

Then Ruby asks the Avalon.

Ruby: Hey, do you have time to duel with me for sparring and evaluation?

Kyoya: Oh, uh, no. But my brother might.

Y/n just nods and wants to try the SGC 00 Gundam. They assembled it and finally they go to the GPD Pod.

Ruby: Are you sure you wanna do this?

Y/n: Yes... 

Then Y/n goes first and scan his Gunpla. When the scan is complete, she began to scan her Gunpla.

Then it began the duel.

Ruby begins combat as she spins the 00 Gundam making it dash back but got hit resulting in it.

Ruby: What are you gonna do now? Your GN Swords will be ineffective against me.

Y/n grits his teeth as he tries to find a way leaving his only weapon Bean Sabers

Y/n: I'll keep fighting. No matter the size or weapon. I'll keep fighting... to pursue, my brother's dreams in GBN.

Y/n's eyes suddenly began to glow and the 00 Gundam rises up and it glowed his whole body restoring itself from the scratched parts to missing plating. 

Ruby: That's... Show me what you got!!

She dashed to him and Y/n began to activate the full potential of the GN Drives.

Y/n: Trans-Am!

00 glowed and picked up its GN Swords and dual wield them and activated the beam saber mode.

https://youtu.be/wuFJj_mHlAo

(A/n: You can see here the animations)

When he did that, the head of her Gunpla exploded.

A.I: Battle ended. Winner Player 2.

They clapped and yelled at the battle. Ruby just mourns about her Gundam exploded, but then Y/n reaches out his hand to her.

Y/n: Ruby... that was a good battle... Let's play together sometime.

Ruby: *changes back to beiong a happy girl* Yeah! But also... WHATWASTHATREDGLOW?TEACHMEHOWTODOIT!

Yang: *giggles*

They all just laughed and the evening shrouded the sky, Y/n is now on his bed, thinking about his experience in GBN.

But then, as soon as he falls to a deep sleep, he sees a strange tree in the dream. 

Then a girl appeared in his dream.  A blonde hair girl with a white clothing and headband, holding a bucket.

She then points to Y/n as the bucket full of unknown water splashes him, and he sees images of events.

He then jolt awake, as he breathes hard. And goes to the a strange room, he opens up the light and there are multiple Gunplas , stored by his brother for many times after customizing the magnum for a long time.

Y/n: 'I need to be stronger now. If its happening in GBN or wherever it is...I need to be prepare.'

He checks himself on the mirror and saw his eyes looks like this.

(A/n: But it's color is green)

His green Innovator eyes have seen, but when he blinked once, it's gone.

Y/n: Ok, time to make my inspiration Gunpla come true, now that I have the SGC 00.

What he didn't know that he was being watched by Kujo. Kujo is happily watching now that his brother has a new goal after finishing his school.

GBN

The Avalon members like Emilia, Karuna, Kyoya, including the former member Hiroto. Are gathered inside the Mobile suit dock. With them are the 1st and 2nd team of Build Divers. Then they see Y/n entered.

Y/n: Okay. I want to show you guys the Gunpla I have built  for me. Just please close your eyes.

They all closed their eyes as Y/n summons the Gunpla he built.

Y/n: Meet the, 00 Core Gundam.

(A/n: It looks like this. Sorry if I don't have the actual image for mine, but let's say this idea, came and inspired from the Gundam Exia and Core Gundam custom build. You can search it up and give credits to the builder for his amazing builds.)

Sarah: It looks amazing!

May: This one, really is like Hiroto's

Hiroto: Oh, wow. He really...

Riku: Wow, this might be the coolest built I've ever seen.

Momoka: But, what's with that ship underneath it?

Y/n: Oh... That, is for the armor sets. 

Emilia: So you really took inspiration from them.

Hiroto: But what kinds of armor.

Y/n: *smug face* Something I've been planning for a long while.

flashback end

Y/n pov

I still remember that day when I enter the world of Gundam universe and Gunpla battle. Until when I saw that dream and transferred into this world that I take my knowledge in Gundams very seriously and take contingency plans.

But all of my thoughts are interrupted by the sounds of cannons aiming at the 3 good people I see below from the skies I'm hovering. 

Flashback

Inside the Walls

???: Damn it! Damn it!

Someone woken up, from a deep crimson pool of blood and darkness place, that's filled with soldier corpses. 

???: *gasp*

It was Eren Jaeger, after his arm got bitten. He's now inside the Titan's stomach. He screamed as he saw the corpses in front of him and looked around him to see more of the corpses floating at the pool of blood. He's now getting traumatic at the events remembering 5 years back.

Eren: 'It wasn't... It wasn't supposed to be this way.'

Then he remembered the graduation.

Eren: 'We had changed over the past 5 years... We trained as hard as we could. We thought long and hard. *remembers Armin not traumatized and the bearded Titan* It was all to defeat them... So that they wouldn't take anything else from us.'

Then he heard a corpse talking to its last breath.

???: It's hot. It's so hot... Save me, Mother. Mother?

Then when he heard the word "Mother" he then starts to remember about his mother, Carla. When he was a child, he was playful with his mother. Before he seeks interest on the outside world.

Eren: 'Mother... Mother?'

???: Save me...

Eren: 'Why did this happen? Why do they take everything from us? *remembers Carla about to get eaten* Our lives *remembers Armin mentioning the outside world* Our dreams...' *tearing up* Why? *trying not to cry* Damn it! Damn it! Damn it all!

He raises his bitten left arm up high to the darkness above as he vowed his will and promise.

Eren: I won't give up! I'll eliminate them all... Every single Titan! I'll kill them all myself!!

As the darkness shrouds the surroundings, a light with a hand shots out, and shots out to the bearded-Titan's mouth. 

Making it fall to the ground, and then it's body is beginning to contort until it bursts out blood and rises the Rogue Titan, Eren. It roared as it was awakened a monster, to kill the Titans. 

Then a Titan sees Eren, and begins to walks to it. Eren sees it as well, it was a dwarf one. He steps to the bearded one's corpse like it doesn't care at all and just focuses its eyes on the dwarf one.

Titan(Eren): 'This isn't your world. not anymore.'

The small one jumps to bite its face off but instead get killed when Eren's punch shoved inside and through the mouth, resulting it's hand get damaged.

Titan(Eren): 'I'll kill every last one of you.'

The dwarf is dead and Eren just gets close to it and starts to stomp it to brutal kingdom come.

Titan(Eren): Get up. *stomp* Get up! *stomp* Let me kill you again! *stomp* And again, and again! *stomp*

As Eren's bloodthirst for the Titans started it all here.

Titan(Eren): You're mine. All of you.

Flashback end

Present

Eren is awake and he remembers the last thing he did before waking up here.

Eren: *creep smile* You're all gonna die.

Armin: Eren.

But then he comes back to his senses as he was surrounded by a bunch of Garrisons. Mikasa notices Eren awake.

Mikasa: Eren! 

Armin: Eren, can you move? Can you understand what I'm saying? Tell them everything you know. I'm sure they'll understand

Eren: Armin.

Kitz the coward is just standing their thinking it was a wise idea to kill the cadets.

Garrison: Hear that? He said, "You're all gonna die!"

Garrison: Yes, I heard him. He's going to devour us.

Eren: 'What are they talking about? Are those blades pointed at us? Those blades are for fighting Titans. What are they looking at?'

All of them are afraid that Eren is a traitor, but for Y/n's eyes, he sees a new bud has begun to grow and about to sprout. Y/n is currently inside the Gundam, hovering above  in a optical-camouflage state.  

Eren: 'What is this?'

Y/n: 'These guys are either corrupt, airheads, or just pure dumb like the Titans. But anyways this is gonna create conflicts in the future, I already prepped the contingency plans for my allegiance to the sides I'll choose. And it will start, right here'

Wall Rose Interior

The trainees who rendezvous to the interior has been prepping for any orders

Cadet Commander: Trainees, keep your equipment  at hand, and stand by!

Connie tells about what happened a few moments ago.

Connie: If we hadn't found the gas with his help, we'd have never gotten out of Trost. Basically, we got lucky. That's it.  

Krista: That sounds terrible. I'm so sorry. We volunteered to run supplies out to everyone, but the situation was so bad.

Ymir: We'd even found some gas we were gonna dole out to you guys, but then everything went to hell bent.

Krista: So, you're saying everyone who isn't here didn't us... you know.

Connie: Yeah.

They just frowned and mourned for it. Ymir asks one of their members.

Ymir: Wait. What about Mikasa?

Connie: Oh, uh. No, no. She's good. She made it in after us with the group Jean led.

Krista: And the 00?

Connie: Uhm. He just stayed there, probably watching for estimating how many Titans are inside now.

Ymir: Hey, Jean! Where in the world's Mikasa? She get hurt or what?

They see Franz, Hanna, Reiner, Bertholdt, Annie and Jean being quiet about the issue.

Connie: Hey. Talk to us.

Jean simply drinks the water on his pouch before he explains what happened.

Jean: I'd tell you if I could. They slapped us with a gag order.

Connie: Whoa. You're joking, right?

Ymir: That's nuts.

Jean: *scoffs* They're nuts if they think people aren't gonna talk. Word will get out, and when it does... Well, that is, if we survive.

Meanwhile atop of the Wall Rose

The other Garrison led by Hannes are pre-occupying the other Titans for now.

Hannes: You gotta hand it to the Engineering Corps for putting the heap of rancid Titan corpses to good use, I suppose. Still just a barricade, though. We can't get too comfortable. Stay on your toes. Whatever happens next, it's bound to happen here. This is the proverbial line in the sand-

Then he sees a Garrison member, feeling down or worried.

Hannes: Hey, something wrong?

Garrison: Sir. My apologies. I completely agree. I'm just a little preoccupied about my friends in the Vanguard. There was a messenger on the way to HQ with this look on his face.

Hannes: Kid. Difficult as it may be, you've got to wrangle your mind to stay focused on what's in front of us.

Garrison: Is it true what they say about you saving those kids 5 years ago, sir? They're cadets now, right? Won't they be at the Vanguard, too?

Hannes looks back to the front and says the answer

Hannes: That's right.

Garrison felt like he just touched a sensitive topis for him, so he apologizes to him.

Garrison: *gasp* I'm really sorry, sir. Don't know why I felt the need to bring it up.

Hannes: They're good. Some tough little kids. Believe me, they know what it takes to stay alive. One of them is just about the best fighter I've ever seen. The other's so stubborn it can drive you crazy. Loads of strength. And their friend's a certifiable genius. They'll be fine. No doubt in my mind. 

Garrison: What about the machine, sir?

Hannes: Hmm...

He can't think of anything other than its eyes show the dedication to eradicate conflict.

Hannes: Knowing that thing, it has what it takes. No matter what they tell to him.

Back in the cowardly trap Kitz made. Eren, Mikasa, and Armin are still stuck there.

Kitz: Trainee Jaeger!  As well as Trainee Ackermann and Arlert... What you're doing right now is an act of treason!

Meanwhile above, he's just listening and observing what happens while eating his own lunch meal.

Y/n: Pfft. As if, you have the guts to even kill a Gundam. You never even got a Titan kill or assist, dummy.  

He just continues watching as he was intently looking at potential targets if ever they raise a conflict even more than it is now. Y/n just observes the 3.

Y/n: Okay. Just like you learn from me when we train... Improvise.

Then he just heard use the word Gundam as a defense, and he squeezes the juice box he has.

Y/n; Using that word as your own defense makes you a target for everyone, including myself.

But then, he heard Mikasa's venomous voice.

Mikasa: *venomous glare* My specialty is tearing through flesh.*raises her blades* If necessary, I am willing to demonstrate it at any time. If anyone would like to experience firsthand, I invite them to be first approach.

Y/n, still camouflaged just laughs like Fon Spaak.

Y/n: *mimic Fon Spaak ego* You would dare Garrison Kitz and Rico, right?! Hehehehe... Hahahaha!!!!

???: Hey, we do that later.

Y/n: I know.. It's just I... or We've been waiting for this moment.

Down below, Eren just asked confused, like he has no memory of what's the context on their situation.

Eren: Mikasa.... Armin! What's going on here?

Armin: Mikasa! You can't fight another human! Where could we run within these cramped walls?

Mikasa: It doesn't matter who I must fight. I won't et anyone kill Eren. I don't need any reason.

Armin: Let's talk this through! No one knows what's going on, so they're ruled by fear!

Eren: 'Am I the only one who thinks I'm not a Titan? Damn it. I don't remember how I got here! I'm too exhausted to move, and if I say anything, they'll probably kill me. Killed by a human? That's ridiculous! What is this about, anyway? I came out of a Titan? What are they talking about?! What the heck is going on?! Wasn't that a dream?'

Then he remembers when he got swallowed and raises his missing arm.

Eren: 'If it wasn't... Then my arm regrew where my clothes are missing... That'd make me just like a Titan! *he looks at his hands* That's impossible... Why would I... Why?'

Kitz: I'll ask you once more! What are you?!

Eren: 'I can't screw up my answer... I wouldn't be the only one to die. *remembers when they're kids* That's right. I've always been just like everyone else...' A human!

Kitz: I see... then don't hate me for this. There's no avoiding it. No one can prove that they are no the devil.

Y/n saw this and prepped his thrusters, preps the protection for the kids and himself. As Mikasa goes to them fast.

Mikasa: Eren! Armin! *drops the blades* We're going up!

Eren: Stop!

Eren is grabbed by Mikasa and then his key appeared at his eyes and remembers a mere fragment of his father, Grisha. 

Grisha: Eren... When I get back, I'll show you what I've kept secret in the basement all this time.

Then his eyes narrows and remembers another one.

Grisha: Never let go of this key. And every time you see it, remember that you must go to basement!

His head began to jolt a little bit.

Grisha: *inserting something inside the syringe* This shot will impair your memory. That's why I can't explain now... 

Then began the full loop of his nightmare back then.

Grisha: Listen to me. *looks at kid Eren with tears in his eyes* Take back Wall Maria and reach the basement. This power will help you then, including the machine you saw! Their memories and your quantum brainwaves will tell you how to use it.

Grisha: Eren! If you get to the basement someday, you'll learn the truth... The path will be harsh and cruel, but you must make it there with him! If you want to save Mikasa, Armin, and everyone else on your own, you must master this power!

He gasps and gets out of Mikasa's clutches and goes to Armin all the while Kitz just ordered to fire all of the cannons and the cannons fires away. Y/n moves fast as Flash or even Sonic, and activates all of his particle vents.

Eren grabs Armin and he's in a protective stance and began to bit his hand. A jolt lightning strike through and a blur appeared and a shockwave created a  huge smoke 2 times the size appears. It began to appear bones and muscles; and also a massive GN  particle forming something.

It then exploded and everyone hears it, including the ones nearby soldiers and Cadets.

Kitz: Did we get him?

Inside Mikasa and Armin are horrified but also surprised. Rico and the other are shocked when the smoke began to fade away as they saw what could possibly be the impossible duo. 

Kitz: No...

They all surprised at what they saw; Eren's half-form and the GN Field of OO Core Gundam: Cannon. With Eren's face showing of scare, while the OO is anger.

The soldiers and others began to scream. But inside the Gundam, Y/n didn't care about it. He just simply smirks like a devil and talks like a madman voice.

???: Let's show them how we do intimidation and things here, Y/n!!

Y/n: 'Yeah, let's show them what it means to face the wrath of a Gundam Meister, Hallelujah!'

As his hairstyle and eye is now different. The right eye has changed to a gold eye on it. His smile is creepy, anyone will give shivers down their spines.

Y/n has unlocked his Hallelujah persona for intimidation use and other stuff.

TBC