Three hours ago.
"70 times 20 kilograms equals 140 kilograms."
a=f/m...
He scribbled and gestured on the ground.
Motomu finished his calculation.
With no other environmental or material influences, under such absolute physical conditions...
He was capable of accelerating a senbon to 121 times the speed of sound!
Yes, you read that right.
A full 121 times the speed of sound!
Launched from Konoha, it would hit the Hidden Sand Village in 20 seconds.
This staggering figure had shocked Motomu so much that he had already recalculated it three times.
Though it was hard to believe, the factual data remained 121.
At least, that was the data on paper.
Motomu took out a senbon and began to finger it.
Mach 121.
41,160 meters per second.
What did this number represent?
He closed his eyes, attempting to simulate the scene in his mind.
0 seconds: A steel senbon needle floats in his palm.
0.05 seconds: 140 kilograms of force acts on the pinhead-sized end of the senbon.
The steel senbon vibrates, and the air in front of it is instantly compressed and shoved aside.
In less than 0.1 seconds, the senbon would vanish from his sight, exceeding the visual limit, while the space where it had been would be compressed into a vacuum, a supersonic boom exploding through the air.
At 0.3 seconds, the true disaster begins.
Wherever the senbon passes, the molecules making up the air have no time to escape and are forcibly compressed and piled up.
Forming a conical shockwave.
A solid wall of impact.
As it passes, the ground's rock is plowed through like tofu, leaving a trench in its wake.
The air on both sides would ionize due to intense friction, trailing a blue-white plasma plume.
Nothing could stand in its path.
"Maybe... I should try it?"
Clink!
The senbon in his hand flipped up.
Motomu opened his eyes, his focus narrowing as his Psychokinesis erupted!
Boom!
A sonic boom thundered!
A blast of air whipped up, sending all the dead leaves in a ten-meter fan-shaped area in front of him flying.
In the eyes of Motomu, whose clothes were fluttering violently, the senbon vanished instantly.
The Psychokinesis cut off, and the residual force carried the deformed senbon as it slammed into the target rock.
'Only less than twice the speed of sound?'
Motomu could not hide the disappointment on his face.
He walked over to the shattered rock and leaned down to pick up the deformed senbon.
"Hiss! It's hot!"
Motomu let go after a quick touch.
The stinging pain in his finger pulled him back from his immense disappointment.
Having put it into practice, Motomu summarized the reasons.
First was the issue with the senbon's material and structure.
At Mach 2, the senbon began to heat up due to air friction; combined with imbalances in material stress, deformation was perfectly normal.
As for the material structure, the forging techniques of the ninja world were roughly at this level.
The only solution would be to use superior materials to endure the force.
Second was Motomu's own limitation: his dynamic vision could not focus on a senbon exceeding Mach 2.
To improve this, he either had to make the senbon larger or bind the activation condition—his attention—directly to the senbon.
After a moment's thought, Motomu remembered Namikaze Minato's Flying Thunder God formula.
A sensory formula would likely suffice.
'And besides a formula, using my own chakra would also be a way.'
Motomu then thought of the Nine-Tails and Naruto; their perception of chakra was also a form of concentrated attention.
Combining the first and second points.
Motomu understood.
For now, his simplest option was to obtain a weapon made of chakra-conductive metal.
It would solve the material science problem and allow him to test chakra-based sensing.
And ideally, it would be a sword.
Being useful for everyday combat was secondary.
More importantly, taking a head from a thousand miles away... wouldn't that be cool?
It would be absolutely badass!
...
"Won't you reconsider? Graduating from the academy at six would be historic!"
"Kakashi is five this year."
"I've even awakened the two-tomoe."
"A single-eye two-tomoe... that is indeed remarkable."
Attempting to struggle a bit more, Motomu waited expectantly for the Clan Leader's follow-up.
"By comparison, is your other eye disabled?"
"Uh, I'm going to be teammates with Kakashi in the future."
"When others strike, they use chakra short-blades, while I just have plain kunai. Wouldn't that make the Uchiha look like we're broke?"
Looking at the silent Clan Leader.
His perfectly calm, square face looked like he wasn't buying it at all.
Motomu felt that this man was even more difficult than the demanding clients from his previous life.
Sighing inwardly, Motomu forced a smile onto his face.
"Then, Clan Leader, I..."
"200,000 ryo."
"Got it!"
Motomu's face lit up with a grin.
Although 200,000 was far from a million, at least it was progress.
He would fleece the rest slowly.
It wasn't like his dear Clan Leader would run away.
He went home.
Pushing open the gate to the small courtyard, Motomu saw his little brother Obito sitting on a stone stool again, looking up at the stars.
"Big brother, Grandma heard you're about to graduate, so she put a drumstick in your lunch box for you."
After a glance at Obito, he opened the lid of the box.
Smelling the aroma of the hot food, Motomu entered a sacred moment of culinary enjoyment.
He chewed and swallowed, even gulping down the last bit of the drumstick bone.
"Brother, are you sure you can pass the exam?"
Motomu tidied up and washed the lunch container.
After stacking it neatly.
He sat back down unhurriedly on the stone chair across from Obito.
"Obito, look into my eyes."
Shing!
The Sharingan activated.
Within the crimson depths, two black tadpole-like tomoe rotated slowly.
"This is—"
"That's right, the two-tomoe Eye of Insight."
"The ninjutsu exam is child's play."
"I'm not playing with you anymore, I'm going inside."
Tap, tap.
Obito picked up the lunch box and sprinted toward the door.
"Do you want it?"
"I do!"
Obito's steps froze.
Just as he was about to turn his head, a massive force struck the back of his neck.
He held on for a second.
But little brother Obito still fainted.
Scanning the surroundings.
Motomu waited for a while, and after confirming no White Zetsu or anything similar was around...
Only then did he trigger Hypnosis layered with Dream Eater.
Facing the Land of Fire battlefield during the Hidden Mist's invasion.
Torrential rain lashed the puddled ground.
In the pitch-black night.
Countless Mist Anbu surrounded them in an assault.
Motomu drove a kunai straight through Rin's chest.
Dressed in black robes, a gaunt Obito stood frozen in place.
Warm blood was smeared on his face.
Obito's black pupils constricted to the size of pinpricks.
His trembling hands clutched his face in shock and disbelief.
Dream Eater ended.
A weakened Obito woke up.
"Big brother, what happened to me?"
"I think I just had a nightmare."
Motomu looked at his little brother; beneath the hands rubbing his face, his eyes showed no change.
'Not enough emotion? Or is an illusion just an illusion after all?'
There was no answer.
Motomu only knew that the combination of Dream Eater and Hypnosis wasn't much help in awakening the Sharingan.
He took half of the 200,000 ryo the Clan Leader had given him.
Motomu reached out and stuffed the money into Obito's pocket.
"Give it to Grandma. Tell her we want to eat something good."
"Bro, where did you get all this money?"
"I awakened my eyes, and the Clan Leader gave it to me."
"Oh, then we really have to thank him."
Looking at the thick stack of bills in his hand, Obito thought for a moment and asked.
"By the way, brother, what kind of gift do you want when you become a ninja?"
A gift?
Motomu really hadn't considered it.
"Whatever. I don't really care about that sort of thing."