With Mangekyo, I Escaped Konoha To Other Worlds [Naruto/AttackOnTitan]

Five minutes Later …

In a village on the Titan Infested wastelands of Wall Maria …

"... That was more than I thought it would be". Seiji let out with labored breaths as he landed on the floor. Behind him, the last Titan fell flat on the earth.

Its blood evaporating in the air.

The whole village was filled with light steam, emitting from several decomposing Titan corpses.

Moving forward, the young Uchiha wiped the sweat accumulating on his forehead and controlled his breathing.

In his line of sight, many half-eaten corpses were all over the battlefield.

Each one wore the distinct uniforms of the scout regiment.

The sight was grim—some bodies were missing heads, while others were torn in half. Leaving half mangled torsos and limbs sprawled across the dirt.

'… That last fight drained nearly everything I had. If more show up, fighting isn't an option'.

After killing all the Titans in this village, Seiji wasn't surprised why these soldiers died.

Ten Titans …. All 10 meter class and above. Three reaching fifteen meters. Judging from his observation, most didn't even have time to react before they were grabbed from blindspots.

Not everyone was Levi.

Seiji contemplated, deep in thought as he walked to the tree where the Fuma Shuriken he had thrown earlier was embedded.

The chakra in his body wasn't much. Just enough to perform one more Jutsu. If the situation called for it, then he would use an Earth release technique to hide underground on the spot.

After all, Titans didn't have the basic reasoning to dig.

Or did they?

While in his thoughts, his movements weren't stagnant as he pulled out the shuriken and sealed it back into the sealing tattoos on his wrist.

Following which, he turned to look around.

The Titan corpses were disintegrating. In time, there would be nothing left. For now, the coast was clear.

Seiji swept his gaze around. His sight falling on a lifeless Titan corpse that had slumped against the side of a broken house.

Down below, an injured male lay against the wall. Precisely the one he had saved earlier.

He rested against a crumbling wall, his eyes closed, but the labored breathing let Seiji know he was still alive.

'…. Alright then'.

The sound of footsteps resounded. The dying soldier opened his eyes as Seiji bent in front of him.

"Hey". He called.

This scout regiment member wasn't that old, perhaps in his mid-twenties. Now that he wasn't being eaten by a Titan, the complex emotions in his eyes had died down, and it seemed that his reasoning had taken hold.

Why say so?

Because all he did was give Seiji a long, hard stare.

Time elapsed. Eventually ...

" … You …". He opened his mouth and uttered a word. Unable to finish it however as what followed was blood pouring out of his mouth.

Seeing his condition, Seiji didn't react.

He had no medical training beyond bandaging wounds, while this man was experiencing serious blood loss.

With a leg and the flesh on his lower rib area gone, a skilled medical ninja with access to high-level medical jutsu was required to save his life.

Seiji didn't meet any of those qualifications, and he didn't have the chakra to spare even if he did.

In a few seconds, the blood spurting fit stopped. The man regained himself, then looked at his savior with narrowed eyes.

"Who … who are you?" He asked with a painful grimace. ".... No, more like what are you?"

Seiji's expression remained impassive. "You wouldn't believe me if I told you".

"...". A moment of silence. Until, the soldier let out a weak, humorless laugh.

"You're not wrong. No human can do what you just did … Not without ODM gear".

It was followed by another coughing fit.

"From your situation, I can tell. What happened here?"

The man was silent, and seemed intent to stay that way. Seiji thought so at first, about to get up when he started speaking.

".... It was a recon mission. The 34th expedition. Our squad was part of the second brigade, on the leftmost flank. The mission had been called off, and we were to retreat. Sadly … ugh …". He groaned in pain.

"Titans were on our return route North. Of the Nineteen soldiers in our flank, I'm the last survivor. The rest were all decimated".

"Nineteen?" Seiji raised an eyebrow. "Plus you, I only counted eighteen".

The man blinked, his face contorting in confusion.

In the earlier battle, he had seen the fight process. It had barely ended moments ago, so how did he have the time to count half-eaten corpses?

Seiji paid him no heed. "... Wall rose is north, huh?" It was the direction the same he was heading.

In response, the soldier looked at him even more deeply, before his expression hardened.

"I see … From your words, you aren't from around here". He previously thought Seiji was something special.

In truth, he was, just not how he initially thought.

"No, I am not". Seiji responded. The man was silent.

"Are you on the side of humanity?" He asked a question that stunned the Uchiha for a moment, who initially thought the man would ask where exactly he came from.

"... I guess you can say that". He thought for a moment and gave his answer.

"That's good".

The soldier said while raising his hand weakly. On his uniform, the emblem with a winged symbol representing freedom was pulled off the piece of clothing.

"I don't know who you are, or where you came here for. But if you truly are on our side, that's all that counts". He said, stretching his blood stained hand out.

"Take this. If you ever reach Trost, help me give it to Commander Erwin. Let him tell my sister that Richard loves her, and I wish … I wish … I could have come back …".

In that moment, Seiji understood.

'… So that's why ….'.

The soldier was dying. On this point, the man himself was very self-aware.

Forget about whether Seiji would answer his questions truthfully. Even if he did, it would've been of no use. In his last few moments, what good would the knowledge be?

Instead, he chose to ask something that would be beneficial to him.

Seiji watched the man grow weaker by the second, as he faltered and struggled to keep the light in his eyes focused.

In response, Seiji took the emblem, his expression unreadable. The survey let out a sigh of relief seeing this. 

"Thank you, for saving me. Even if I wouldn't live long after".

Time seemed to slow down infinitely as his brain went into overload and blanked out at the same time. In that one moment, his life history flashed before his eyes.

His dead father, deceased mother, and loving sister. The last was still alive, barely a teenager who still cried whenever he left and always looked forward to him coming home.

He had promised her he would. Every time.

Unfortunately …

'… I'm sorry Mina, I … I broke my promise …'.

Then, with a final shuddering breath, he went still.

Seiji stared at the lifeless body for a moment, his features betraying no emotions. Gently, he reached out and closed the man's eyes with two fingers.

"Rest in Peace. I do hope you find it".

Before he awakened his memories, Seiji had been a participant of the Third Ninja war.

He was no stranger to the death of people around him.

Rising to his feet, he turned his attention to the remnants of the survey corps equipment. Most of it was destroyed, but one set remained intact.

Alongside the emblem, he carefully sealed it into a scroll for later use.

---

Inside one of the less damaged houses, Seiji sat cross-legged. A sealing scroll was opened beside him, indicating he had taken out part of its contents.

He had.

Upon leaving Konoha, Seiji had bought six storage scrolls and numerous resources, while also converting his village merit points in exchange for Fuinjutsu knowledge.

Fuinjutsu, also known as Sealing Art.

A class of Jutsu all Shinobi more or less knew the basics. (Unless you are Rock lee)

Its fundamental use was for sealing objects, energy, jutsu and even living beings into other objects. The last part involved the advanced forms of sealing techniques which wasn't available to everyone.

Seiji included, as even the full exchange of all his accumulated military merits weren't enough.

As a technique that required heavy knowledge and advanced chakra control, its difficulty could be imagined.

Hence, most Shinobi only had access to the basics. Primarily limited to the use of already prepared summoning scrolls with Fuinjutsu embedded on it which were sold in large quantities by The Village.

Shinobi, who didn't choose Fuinjutsu as a specialty, wouldn't spend their time learning sealing techniques. Not even Jonin who needed versatility as a requirement to reach their rank. (In the concept of a Jonin needing to be versatile, there were always exceptions. E.g. Might Guy)

Knowing there was every possibility that he would have to escape Konoha soon, Seiji had decided to do the opposite. Spending little of that period familiarizing himself with the Sharingan and more gathering resources and the Fuinjutsu knowledge needed to haul it.

Thus learning the B rank Jutsu,

---- Kuchiyose: Raikō Kenka [Summoning: Flash Blade Creation] ----

Alongside the higher basics of the,

---- Fūnyū no Jutsu [Enclosing Technique] ----

Within three months.

Then he emptied his savings to purchase Food, water, water purification tablets, canisters, medical supplies, poison neutralizers, emergency first aid kits, herbal remedies, tents and sleeping bags. All stuffing them into one scroll.

The second scroll carried his Family legacy. Seiji's parents were both Jonin, hence they left behind a lot of valuable knowledge in case a time came where for some reason, they wouldn't be there to give it themselves.

Jutsu scrolls.

Ninjutsu for the three chakra attributes of Wind, Fire and Earth which he possessed.

Kenjutsu, Genjutsu, Taijutsu, Shurikenjutsu.

Uchiha clan Sharingan usage notes. Chakra Nature Transformation Notes, while also carrying the Fuinjutsu scrolls he had packed up as well.

The third scroll carried the vast majority of his weapons. Kunai, Swords, Explosive tags, Shuriken.

The other three scrolls were extras. One currently carrying his Nana's corpse and another holding the ODM gear.

At the moment, Seiji had taken out several compressed biscuits and ate while resting to replenish his chakra.

Meanwhile, he began to analyze his current situation.

To sum it up, he was trapped here. Trapped in a fictional world from his past life.

The limitations of the Interdimensional Gateway had already been made clear. To return to the world of Naruto would require half a year of waiting in this world.

Not to mention the time difference of one to five. Two and a half years would have passed back in Konoha.

If he remembered right, Sasuke who just witnessed the massacre of his clan was still in his first year of Ninja school. The time distortion would mean he would return Two and a half years before the start of the Naruto series.

Aside from Naruto bearing the Hatred of the village, not much happened during this time.

Of course, that wasn't the issue.

From Seiji's understanding, Itachi would report to the Third Hokage after realizing he couldn't find him.

Then, he would be declared a Missing Nin of Konohagakure. Either that or the whole thing would be kept under wraps due to the fact that the Uchiha clan's intention to rebel was kept a secret and proclaiming an Uchiha who ran from being killed by Itachi a rebel would look strange.

The latter option was slim. Nevertheless, Konoha would definitely send Shinobi to search for him, either openly or secretly.

A rogue Uchiha who knew the truth could potentially become dangerous to the village.

Perhaps Itachi would take it upon himself to search as well.

Of course, finding him would be a foregone conclusion. After two and a half years of silence, the heat following it would have calmed down.

What would happen after that was what Seiji needed to decide on.

When he returned, he would have to deal with Itachi, kill Danzo and destroy Konoha in the process.

Perhaps also Kirigakure, who were responsible for his father's death and sand Shinobi village responsible for his mom's death during the third ninja war. But only on the premise that he had enough strength to actually accomplish it.

Which led to the problem.

Six Months was a short time and the current him was far too weak. Not to mention he hadn't familiarized himself with its power, simply relying on Mangekyo awakening was far from enough.

The Mangekyo Sharingan, while powerful, was flawed. Using the eyes alone and the techniques that came with it, Jonin and Elite Jonin would be no match for him.

That, however, would change once he met truly powerful opponents with skills surpassing regular Shinobi.

Sasuke's future battle at the Five Kage summit was a prime example. Even with the Mangekyo and offensive pupil techniques like Amaterasu, he wasn't able to defeat a single Kage on his own.

Beaten by Raikage, blocked by Kazekage, Nearly melted by Mizukage and would have been vaporized by Tsuchikage if not for Zetsu.

Killing a bunch of Samurai and defeating a few side characters was the greatest of his accomplishments in that reckless attack.

That was the Sasuke who defeated Orochimaru and Deidara. With mastery of Lightning style chakra form change, outstanding Kenjutsu techniques, exceptional speed and strength, alongside Jutsu like Chidori, Kirin, Curse Seal, snake summoning, snake substitution, strong combat experience and an outrageously strong will.

All this, paired with those eyes, and he still lost. In comparison to Seiji himself, Sasuke eight years later, who hadn't awakened Mangekyo was better than him in every possible way.

Technically speaking, he was 17 years of age and was currently older than Sasuke would be in eight years, yet his overall prowess without sharingan was still Chunin. Perhaps special Jonin.

Seiji's memory of the anime was a wake-up call. In the Ninja world, his foundation was shallow.

Rushing into Konoha to fight against an entire Hidden Village thinking he was Invincible with nothing but a pair of consumable eyes would be suicide.

At best, he would end up running away like Sasuke did. At worst, he would lose his life.

How embarrassing. The pride of Uchiha must not be sullied.

The only exception would be If he awakened Kamui like Obito did or something similar, which would allow him to run rampant in the Ninja world.

Unfortunately, ….

'…. My eyes … '. In the thrashed room, the young Uchiha reached out to touch his eyes. It had been several hours since his arrival in this world, long enough for him to understand what pupil techniques he had awakened.

Neither eye held space time Techniques, however, Seiji wasn't sure he would exchange it even if he could.

---

Left Eye: Kagami Utsuchi (鏡の土) – "Mirror of Earth"

Main Function: The left eye grants the ability to temporarily display abilities within the user's vision. The user can activate this eye to project or mirror the powers of others for a limited duration. These abilities are temporary, giving the user access to a wide range of powers as long as it is still within sight.

Right Eye: Junen no Sōzoku (十年の創続) – "Ten-Year Creation Continuity"

Main Function: The right eye allows the user to permanently copy a single ability once every ten years. The user must wait a full decade before they can acquire a new ability in this manner, making it a rare and strategic technique that requires patience and careful consideration.

----

After repeated confirmation, Seiji didn't even know which category of Jutsu these techniques fell under.

Offensive? Support? Utility?

The left eye enabled him to replicate any ability that was displayed within his line of sight and use it without constraints as if it were his own.

It didn't matter whether they were bloodline techniques, or abilities that couldn't be mastered without special prerequisites.

He could replicate them all. Regular Tomoe Sharingan could only copy Jutsu. No Kekkei Genkai.

Even those Jutsu had restraints as the copier must have the necessary qualifications to perform such Jutsu.

Like the corresponding Chakra nature affinity, Chakra control, unique body physiology, and so on. Without it, copying the hand signs and Chakra flow would simply be useless.

These restraints didn't disappear even after awakening Mangekyo, Eternal Mangekyo, or Rinnegan.

Many Uchiha only had one chakra attribute. If they had two, one was Fire. Sasuke Uchiha only had Fire and Lightning. Itachi Uchiha, Fire and Water.

And Kakashi who had all Five alongside their corresponding Nature Transformations became known as a copy Ninja with more than a thousand Jutsu under his belt.

An outsider gained more fame with the Sharingan than the actual Uchiha.

Moving on. His left eye allowed him to ignore such constraints entirely.

This …. Wasn't this basically the greatly enhanced version of the Sharingan's copy ability?

Of course, no technique was invincible. Like all Mangekyo, the Limitations were there.

The Left eye could only copy abilities temporarily. How temporary this was would need to be further explored. Whether there were limitations on the copied ability also needed to be explored as well.

Would he lose the abilities as soon as the target was out of sight? And to what extent could the replication achieve?

Ultimately, it granted Temporary power and would change depending on the strengths of the opponent he faced.

The right eye, however, was the opposite.

Junen no Sōzoku (十年の創続) – "Ten-Year Creation Continuity"

It granted him a permanent ability addition to his arsenal, permanently.

Once added, It would become a part of his skill set like any other ability, without requiring The Mangekyo to be activated to use it. Just chakra.

If its potency was anything like Shishui's Kotomatsukami which shared a similar cooldown period, then this could potentially be the most powerful Mangekyo ability to ever exist.

In addition, the combined use of both eyes granted an additional power, just like Obito.

Eikyu Zoshoku (永遠増殖) – "Eternal Replication"

Main Function: When both eyes are used in tandem, they grant the endless replication of physical matter. Allowing its user to duplicate and generate physical objects indefinitely.

Back in the forest, Seiji had used this ability to kill the first Titan.

By subconsciously copying a tree and focusing the point of generation within the Titan's stomach.

Then, it generated instantly, a tree growing out of nothing, blowing up the Titan from inside out.

Come to think of, Seiji realized that these abilities were better than Sasuke's and Itachi's. Perhaps even Obito's.

However, the direct overwhelming offensive prowess wasn't granted. In a fight with Shinobi, especially ones like Itachi, Obito and Danzo, nothing was guaranteed.

It was more than a battle between Mangekyo Sharingan. Even with his eyes, killing Itachi wasn't guaranteed, not to mention Danzo, with a literal arm full of Izanagi.

He would run out of pupil power before he could come close to flattening konoha and ultimately run blind.

With all these points, Seiji knew what he had to do.

The classic Training Montage. He would use the available time to improve himself as much as possible just like Sasuke did.

Increase his Taijutsu prowess. Speed, strength, and stamina.

Master the jutsu scrolls he had brought along with him. Ninjutsu, Genjutsu, Kenjutsu ...

In a Ninjutsu variety, forget about Madara's fire style power, but he should not be weaker than Itachi. His proficiency in Genjutsu must be good enough to avoid being defeated by a single look like Orochimaru and Kakashi.

Alongside Mastering Nature Transformation of Chakra attributes.

He planned to give himself from six months to a year. Following which, he would either return or travel to New worlds.

In the world of AoT, as long as he still had chakra, he had nothing to fear. It wasn't an exaggeration to say he was the strongest being in this world just be virtue of the body flicker technique, Kenjutsu and the dynamic vision his eyes granted him.

Hence in the coming time, he would work himself to the bone, honing his eyes, refining his chakra and increasing his combat prowess until he squeezed every advantage he could get out of this world.

At that moment, the resting Uchiha opened his eyes, surprised to find his chakra capacity refilled.

It had only been a few hours. Usually, it would take more than a day and a half of rest to return to full capacity.

Even more surprising was it didn't stop there. Instead, he could feel the vibrant activity in his body cells, releasing more energy with each passing second.

'Ah! There's my bonus chakra'.

The boost in mental energy would lead to a growth in chakra reserves. And what greater boost could there be than the increase in Yin attribute chakra provided by the Sharingan evolution?

It didn't matter how bad they were before, but once their eyes were opened, all Uchiha would become geniuses.

Seiji slowly stood to his feet as he felt his reserves passively increasing at a much faster pace than his active refining of it.

The increase in Chakra wasn't immediate. After all, that much energy couldn't suddenly appear out of nowhere.

But just from this pace, his current Chakra reserves would multiply ten times on the original basis by this time in Two days.

Logical, since his Mangekyo abilities consumed so much energy. Not to mention Susanoo, the literal embodiment of solidified chakra.

In hindsight, he should also receive an increase in physical prowess.

'... I see. No wonder Itachi alone could slaughter the entire clan without utilizing a single Jutsu. This power truly is incredible ....'.

He thought as he looked out the window, using chakra to boost his five senses.

It was getting dark out. Throughout this time, no Titans had returned to the village again.

With his chakra replenished, he couldn't stay here anymore. After all, night would soon fall, and he would prefer spending his evening on a bed and not in a sleeping bag.

"... Alright then, just one more thing before I leave".

He uttered, moving out of the house and out of the village.

Upon reaching a secluded area, he quickly placed his hands together and performed hand seals.

---- Doton: Doryūha 土遁・土流波 [Earth Style, Earth Flow Wave] ----

The ground instantly split open, creating a large hole in the soil. The Earth release he performed was a C rank technique. Common to Chunin and above with most Genin.

And his reason for performing it was simple.

With the hole made, the young Uchiha took out a sealing scroll, rolled it open and infused chakra.

With a puff of smoke, a corpse appeared. It was his grandma's, Asami.

Gazing upon her smiling face, , the unsettling feeling of loss he had placed aside rushed up again like a tidal wave.

Taking a deep breath, he restrained the emotions within him and placed her into a stone coffin.

It was improper to carry her body around in a scroll like luggage. Burying her was the least he could do.

"...". A suffocating silence engulfed the atmosphere, followed by a restless wind stirring.

This wasn't an illusion. Presently, Seiji stared at the simple grave he had created, and his eyes involuntarily became scarlet.

The chakra pressure in his body was released uncontrollably as he clenched his fists tightly.

Though it was nowhere near the level of Hashirama Senju though, and couldn't send out torrents of wind pressure.

"... I swear to you, grandma …".

The final rays of the setting sun illuminated his features. "... I will do as you asked. I will kill Itachi, destroy Konoha, and revive the Uchiha clan ….".

".... Even if it's the last thing I do". No one could understand how he felt. Not Sasuke, not Naruto, not Obito, not Nagato. None of them would understand the despair of knowing what would happen and being unable to change it.

Itachi destroyed his clan for Konoha, for Sasuke. All to prevent war, he sacrificed his clan and the ones he loved for the greater good. For the well-being of the village.

Even if they would never know of his efforts. A true Konoha Shinobi to the last breadth, even better in this regard than Shishui, his teacher.

As for whether his actions were morally right or wrong? In a world where children were trained to kill from a young age, that was debatable.

As a Transmigrator, Seiji knew this. Hence, In his last life, he understood Itachi's burdens to an extent. Now? He couldn't care less.

'… This is probably how Sasuke feels, huh?' he thought to himself with a self depreciating smile. In his eyes, the naked murderous intention emanating without reservation.

The Mangekyo was most likely affecting him at this point. Twisting his mind and fueling his hatred.

He cared less for this as well.

Unlike Sasuke, unlike Obito, unlike Nagato, he had plot knowledge. And in time, he would make them all feel the same pain he did.

All of it, Ten times over. '… I swear it'.

He moved his hands, the hole was covered up. Using Earth style, he manipulated the earth and created a large Tombstone.

On the top, several words were written on it.

[To my beloved Nana, a woman who didn't belong to this world]

Doing this, he closed his eyes, took a deep breath and opened them again.

The Sharingan was gone, alongside the intent to murder everything in sight.

"... Alright, let's get out of here". It was time to start fulfilling his goals.

Locating Wall Rose for one. Two, understanding the timeline.

The Attack On Titan world was quite weak compared to the Ninja world. A moderate Shinobi clan would be able to clear all Titans on this Island given enough time.

However, his time here wouldn't be useless.

There were things he could gain that would greatly improve his strength.

Junen no Sōzoku (十年の創続) – "Ten-Year Creation Continuity", his right eye technique had a ten-year cooldown.

The sooner it was used, the earlier he could look forward to its second usage. And he already had the perfect ability in mind.

He thought as he crossed over a river. The moment he did, his steps paused as he noticed something in the soil.

Bending down, he examined them and easily determined what they were.

"Tracks?"

Footprints to be exact. Seiji couldn't help but raise an eyebrow.

These weren't old. Quite the contrary, they were Fresh, possible no more than a few hours as well, meaning that someone had ….

In that moment, the boy remembered something.

" ..... Of the Nineteen soldiers in our flank, I'm the last survivor. The rest were all decimated ….".

"Nineteen? Plus you, I only counted eighteen corpses …".

It was a brief flashback to the discussion he had with the soldier.

"Oh …". The realization hit. Earlier, he had noticed eighteen survey corps bodies instead of nineteen. The dying soldier speculated that one was eaten whole.

Seiji walked a few feet forward. What came into his sight was a damaged ODM gear and ratchet belt on the floor.

Followed by footprints running into the distance.

'… Guess he was wrong then …'.

In the 2nd brigade of the Leftmost Flank, someone had survived. Abandoning their damaged ODM gear as it would be of no use.

The footsteps meant the target was travelling on foot. If that was the case, then whoever this person is, he is most probably dead by now.

In Titan infested lands, without ODM gear, weapons, or a horse, death was inevitable.

However, "The tracks lead North". It was clear that this person was heading in the direction of the walls.

Death was a certainty, of course. Seiji knew that, and the person in question probably knew as well.

Concluding this, he turned to take one last long at the village before heading in the same direction.

Who knows, maybe he would catch up before he/she got eaten by a Titan.

----

POV change

Meanwhile, ….

"My name is Ilse Langnar".

In the Titan infested wastelands of Wall Maria, hidden beside a tree, a female member wearing the standard uniform of the survey corps jotted words unceasingly in her diary.

"I've lost my horse in the world outside the walls".