"Back then, you told me it'd only be three years. Then three more. And another three after that!"
"It's been nearly ten years now, Yagura!"
On the rooftop, a young man in a gray Konoha combat uniform leaned on the railing, his brows tightly knit. He was agitated—his voice rose in volume and his gestures grew more intense with every word.
Standing beside him was a boy half a head shorter, around twelve or thirteen, with a deep stitched scar across his face. He looked equally annoyed.
"Could you maybe treat me with a little more respect?" the boy snapped. "I'm the only person in the entire Mist Village who knows who you are. If I go home and burn your file, you'll live as a Leaf ninja forever—and I won't have to deal with this crap anymore!"
"So what do you want from me?" the older teen slapped the railing and pointed to the Konoha forehead protector on his head, voice rising even further. "Am I supposed to chant 'I'm a Mist ninja!' to myself every day? Dream about the Will of Water in my sleep?"
He pointed directly at the boy—Yagura—and flared five fingers in front of his face. "Five years old! I was five! Barely out of diapers when you sent me to Konoha as a spy. I've been undercover longer than I ever lived in the Mist. I can't even remember my parents' faces. And now you're mad at my attitude?!"
Yagura tried to explain. "That's because you were emotionally stable and mature for your age. You were the top pick in the village-wide—"
"Fail the test and you die. Think that helps with emotional stability?"
"..."
Yagura fell silent.
The Bloody Mist wasn't built in a day. Even before its official rise, the village was already infamous for twisted decisions—sending children as spies wasn't even considered extreme. Tailored "miniature" agents for specific enemies had existed before.
Yagura might be a jōnin and this man's handler, but even he hated how the system worked. Still, as a shinobi and superior, he couldn't show it.
So, both of them quietly turned away, staring off at the distant rooftops of Konoha.
Another long silence.
Ten years...
Yagura pulled a candy from his pocket, unwrapped it, and popped it into his mouth. The weight of that number pressed heavily on him.
At just twenty, Yagura was already one of the Mist's most promising jōnin. He was the third direct contact assigned to this deep-cover agent.
Unfortunately, the first two had been killed—one by Konoha's ANBU, the other by the Uchiha Police Force. And now it was Yagura's turn.
He hadn't even known about this spy until he gained access to the Mizukage's top-secret archives.
Codename: Deep Sea 004
Current Name: Sazahara Mu
Age: 15
Specialty: Water Release, Taijutsu
Rank: Chūnin of Konoha; Assistant Intelligence Analyst, Rank II Advisor
Time Undercover: 10 Years
In a world run by ninja, things like infiltration, espionage, torture—they were just business as usual.
No one batted an eye if a spy was under ten years old. A kunai thrown by a four-year-old could be just as fatal as one thrown by someone fourteen.
Sometimes even more so.
But even in that cold world, agents like Sazahara Mu—who had spent a full decade consistently embedded in the heart of an enemy village—were incredibly rare.
You could train skills and brainwash loyalty, but emotional maturity couldn't be mass-produced. Most child operatives were one-time-use tools. The very few who survived their missions and managed to escape were already considered miraculous.
But Sazahara? He didn't just survive—he thrived.
He infiltrated Konoha, avoided initial sweeps, and rooted himself in the village. Enrolled in the Academy. Became a full-fledged ninja.
And during all of that, he kept feeding intel back to the Mist.
His file was classified at the highest level, restricted to direct Mizukage contact. Only one handler at a time could know he existed.
An assassin's blade hidden in the heart of Konoha. Rare in the entire ninja world.
Especially now, Year 39 of the Konoha Calendar, the third year of the Second Great Ninja War.
The war, started by Sunagakure and fueled by Amegakure and the Five Great Nations, had plunged the world into chaos. Even distant Kirigakure faced dual pressure from Konoha and the Cloud.
To the unstable Third Mizukage and the fragmented Mist leadership, that pressure was unbearable.
Konoha had to be weakened.
CRACK—the candy snapped between Yagura's teeth.
He finally broke the silence.
"Ren," he said softly. "No matter what happens… some things only you can do."
Sazahara Mu turned to look at him.
To an outsider, that small gesture might've meant nothing. But for someone who lived on a razor's edge, Yagura's slight compromise meant everything.
When Sazahara spoke again, all of the earlier rage was gone. Replaced by chilling coldness.
"Because my last few missions were too aggressive, Konoha's ANBU have intensified internal sweeps. Even Root is moving. At least two search teams are hunting for signs of me."
"So, limit missions to once every six months."
"Reduce contact with me as much as possible."
"And by the way, your predecessor never paid me for the last job. Don't forget."
"..."
Yagura didn't respond, just stared at him.
Sazahara didn't press. He simply waited, unmoving.
Finally, Yagura reached into his cloak and pulled out a scroll.
"I'll report to the Mizukage," he said. "Once you complete this mission, no one will contact you for three months. You'll get your payment after that."
Sazahara Mu took the scroll.
His demands had walked the fine edge of what was acceptable. Getting them approved wasn't the point—he needed to assert his position, prove his value.
Until the war ended, the higher-ups wouldn't touch him.
After the war?
That was out of their hands.
He opened the scroll, scanned the contents, and handed it back. Then—with a puff of smoke—he was gone.
Yagura stood in place, eyes locked on the spot where the spy had just stood.
In truth, before Yagura had left the village, the elder Genji had given him one more secret task: investigate why the previous two handlers had been exposed.
Clearly…
The higher-ups believed Sazahara's "time of use" was almost up.
A ninja doesn't need proof. If you can't be trusted, you die.
They'll likely kill him once the war is over.
Despite all the intel he's been given…
"Hero"...?
For a brief moment, Yagura felt a surge of bitterness, a heavy hopelessness.
He exhaled.
"...Sorry."
Konoha — Third Floor, Hokage Building
Intelligence Department
Sazahara Mu was hunched over a desk, double-checking logistics spreadsheets. Suddenly, he jerked upright like someone had sat on a tack. His pen paused mid-line.
He shifted in his seat.
Memories from his shadow clone surged into his brain.
New handler, huh?
Too bad—this one's going to be a pain.
Fourth Mizukage...
Sazahara mused as he resumed writing, his hand moving automatically as he pondered what Yagura's arrival meant.
He had been chosen for this mission because of his unnaturally mature mind, not some innate genius, but because…
He had lived a previous life.
A reincarnator.
When he first woke up in the Naruto world—specifically in the rarely touched Mist Village—he thought he could use his future knowledge to climb the ranks.
It worked.
A little too well.
They noticed him alright—just not in the way he'd hoped.
Who the hell volunteers to go deep cover in the ninja world?!
No one. Because spies in this world all end up dead!
So no, this lifestyle couldn't last forever.
Even a cunning rabbit has three burrows. He needed a way out.
What he wanted most right now was to wrap this up, return to the Mist as a decorated war hero, and retire before the Bloody Mist era began.
Then? Live a peaceful life as a wealthy Mist retiree with a harem and hot springs.
After all, as long as you didn't get involved with Kaguya's soap-opera family drama, the ninja world was survivable!
...That is, if the Mist didn't throw more trouble his way.
Yes, he'd thought about rebelling, escaping, or even defecting to Konoha.
But the Mist had layered seals all over his body—brain, heart, even tongue. At least three he could feel. There were probably dozens more etched into his chakra system.
Just like he could exploit the Mist's desperation to push back, they could squeeze him dry just as easily.
And the Five Great Nations? Still in chaos. No prisoner rights. Spies were tortured, dissected, and used as lab material.
Running? Suicide.
The only saving grace?
His system.
"Today should be the day…"
His hands moved faster on the forms as anticipation built.
Once the last stack of papers was done, he slapped his pen down, grabbed his bag, and launched himself straight out the window.
"Hey! Sazahara-kun—!"
His boss, a panda-eyed man with pineapple hair, sprang up from his desk and grabbed another stack of files.
"You're skipping work?! Right in front of me?! I haven't had a day off in 87 days!"
"This counts as leave! I'll make it up tomorrow!" came the distorted voice of Sazahara Mu from a distant street corner.
Nara Koshimo slumped into his chair and stared at the mountain of paperwork.
He's gonna pay for this.
I'll drown him in desk duty!
Home – Evening
"I'm back!" Sazahara Mu called out as he stepped inside.
"Huh?" a young girl's voice replied.
A slim teenage girl with an apron peeked out of the kitchen, her face lighting up.
"Onii-san! You're home!"
She rushed to him excitedly. "You're early today! Were you tired? Want dinner first? A bath? Or..."
Bonk.
He flicked her forehead.
Sazahara feigned annoyance. "You know it's illegal to tempt adults. Uchiha Police would arrest you! Don't frame your dear brother, Yukie!"
"Hehe~" Yukie took his bag from him with a smile. "Onii-san came home so early today… Don't tell me you already knew I got the last pack of premium beef at the market?"
"Or maybe you even knew about the sukiyaki dinner—?"
"Oh? Sounds fancy." Sazahara grimaced. "Too bad—I've got new ninjutsu to test. You eat without me."
There was a faint distance in his tone.
"I see..."
Before she could say more, he was already heading upstairs.
Yukie Sazahara. Age twelve. A recent academy graduate.
Despite the war, Konoha still had enough resources to shelter new genin. She was being mentored, not sent to the frontlines yet.
Why did a spy like him have a little sister?
Simple.
Becoming a "true Konoha native" meant jumping through countless bureaucratic and psychological hoops.
But if you inherited the name of a family who had lived in Konoha for decades, lost your parents in the war, and had a dependent little sister?
Your background checks got much, much easier.
Orphans and loners were always the first suspects. Many got picked up by Root for that reason alone.
People with no weaknesses were dangerous.
Luckily, when he first infiltrated Konoha, he found such a family.
Parents dead, older brother crushed in a building collapse, baby sister left crying in a stroller.
Perfect cover.
From that day on, he became Sazahara Mu.
And Yukie? His "real" little sister.
Of course, he never truly trusted her. He wasn't dumb.
Because one day, he was leaving.
He didn't notice her eyes darken as he turned away.
Back in his room, he double-checked every trap and seal. Once confident, he sat cross-legged and tried to calm the excitement bubbling in his chest.
He closed his eyes.
"Panel."
A screen lit up instantly.
[Minor Mode Unlock Countdown]
[00:00:09]
Yes.
Freaking Minor Mode.
No matter how many times he saw it, he wanted to scream.
Sure, he had trained, killed, and survived since childhood.
But his cheat system? Age-restricted to 15+!
Utter nonsense!
He had been a greasy old man before he died—who was this protecting?
But finally—finally—it was time.
9...
8...
7...
3... 2... 1—
System: ONLINE!
His vision was engulfed in white. A soft, melodic female voice whispered in his mind.
"Are you my Master?"
"Yes," he murmured.
She continued like a stage actor giving a dramatic monologue.
"Oh~ Subarashii!"
"Just transmigrated and already awakened the legendary Sazahara Friend Notebook System! What do you have to fear? NOTHING!"
"First, the Hokage, kick Madara, rise, and beat down Kaguya herself!"
"You will puff the world into submission!"
"Sazahara Mu, when will you become Number One in the ninja world?!"
"TODAY!!"
It was thunderous, ridiculous, utterly absurd.
And Sazahara?
His glowing eyes went blank. His confident grin turned stiff. His face, pale as a ghost, seemed... broken.
The silence was deafening.
"...?"
He had a very bad feeling about this.