Jonin were already top-tier forces within a village and a clan, worth serious attention.
In only three days, Uchiha Senya had risen from a genin with decent taijutsu to this level.
Even a prodigy like Kakashi would be left in the dust at such speed.
Still, in the late chaos where Kage-level fighters were everywhere and jonin were nothing, Senya's present strength was something Madara could swat aside with a single move.
There was no room for him to relax.
Time might still be on his side, but he could not afford to slack off for a moment.
"Raikiri is lightning style and lives on speed. Driving it with a one-tomoe Sharingan is still a bit forced."
After felling another tree with Raikiri, Senya analyzed calmly.
The technique's power was bound to the Sharingan.
Kakashi had once separated Naruto and Sasuke with ease using it.
Only higher stages of the Sharingan could unleash a faster, deadlier Raikiri.
He glanced at the moon and stopped.
Raikiri made a lot of noise. More practice might draw patrols.
He erased the traces of training and hurried off.
A shadow flickered past the Guard Tower gate.
Senya had returned to his room.
Uchiha Jin's quarters were, as always, silent.
Senya changed into clean clothes and settled down to draw in the natural energy in the air.
Soon the moon slipped away.
Midnight had passed.
At the system's prompt, he checked in at once.
"System, begin today's check-in."
DING! Check-in successful. Congratulations, host. Reward: Two-tomoe Sharingan.
His eyes lit up.
Ask and it appears.
Without hesitation he opened the sphere of light in his mind.
A cool chakra surged into his eyes.
An odd, stinging ache coiled behind his lids.
He forced himself to endure, shut his eyes, and drove chakra from his whole body into them.
From past experience, the Sage Body's chakra aided the awakening and eased the discomfort.
A few minutes later the pain ebbed. He snapped his eyes open.
A denser, colder chakra formed in his irises.
The spinning single tomoe slowed, and beside it a second tomoe pressed forth.
Two-tomoe Sharingan, achieved.
"Subarashii."
Thrilled, he stood and went to the window, tasting the new vision.
Wider insight, higher resistance to genjutsu.
At his urging, the two tomoe whirled and began to show their might.
"I can feel it. My Raikiri dash range has at least doubled."
That meant his kill window had doubled as well.
He did not rush to the training grounds to test it. Dawn was close and the grounds would be crowded.
His clone was still on duty.
Sensing the situation, he stayed in his room, absorbing natural energy while adapting to the two-tomoe Sharingan.
He would head out once night fully fell again.
...
With steady, full days of training, his power firmed up.
Time raced by.
Two years passed in a blink.
Nothing special happened at the Guard Tower.
On the borders, though, the Rain and Fire countries were past the point of reconciliation.
The Wind country stirred as well. Under Chiyo, its forces gathered.
The Second Great Ninja War was about to erupt.
Sarutobi Hiruzen and Shimura Danzo worked themselves ragged.
The Uchiha began their own mobilization for war.
Uchiha Fugaku had risen to chunin and would head to the front to earn honors for the position of young clan head.
None of this concerned Senya, written off as a layabout at the Guard Tower.
The elders had no intention of sending the tower to fight.
This war belonged to the Legendary Sannin and Konoha's White Fang.
Senya kept his discipline, checking in and training every day.
At the training grounds he checked in for a B-rank Fire Release.
At Ichiraku Ramen he checked in for advanced ramen technique.
At the dango shop he checked in for an advanced shogi skill book.
At the Hokage Rock he checked in for a Konoha sword style.
At the village gate he checked in for intermediate fuinjutsu.
At the Hokage's office he checked in for the three-tomoe Sharingan.
...
Across these two years, he laid foundations and advanced step by steady step.
He fully mastered the three-tomoe Sharingan and could rebound most genjutsu.
His Sage Body reached forty percent completion.
Then he hit a bottleneck. The ambient natural energy was no longer enough.
He was considering entering the shrine or seeking a holy land to cultivate.
He also took a few out-of-village missions, honing real combat while keeping risk as low as possible.
As for strength, from ninjutsu application to chakra reserves, his overall level had reached quasi Kage.
He could defeat jonin with ease.
Against true Kage-level fighters he still lacked depth.
That kind of seasoning could not be faked.
It was why he still hovered at quasi Kage after two years. He needed a catalyst.
Perhaps once the Sage Body rose higher, or when the Mangekyo Sharingan opened, he would step across.
"Not enough. Still not enough. Being quasi Kage might put me first among my peers, but it is not enough to survive this world."
"I am still too weak."
He spoke under his breath.
Knowing what the future held, he understood that this power would be nothing before Infinite Tsukuyomi.
Of course, he only said this in private. If his peers heard, they would choke.
Two years after graduation, a quasi Kage expert, and he called himself weak?
What were the ones still stuck at the chunin exams supposed to do?
If he was weak, they did not even qualify as weak.
Most academy graduates, barring accidents, would never become jonin.
Once they passed their prime, they would decline, spending life as chunin or genin.
...