Yoru returned to the small lakeside.
Tobirama Senju truly was a genius, his Water Style techniques were unlike anything else.
Most Water Style jutsu relied on blunt force impact.
But Tobirama had developed a method similar to a centrifugal pump, using chakra rotation to massively increase water pressure and launch a water jet at extremely high initial velocity.
Still… that wasn't the limit.
Yoru had a new idea. If one centrifugal water vortex worked, then two vortices, simulating a gear pump, should be even stronger.
In his previous life, gear pumps produced far higher pressure than centrifugal pumps.
Two gears rotate in opposite directions; where their teeth mesh, a vacuum constantly forms, creating tremendous pressure.
After forming the seals, Yoru gathered a small amount of water in his mouth. No need to store too much, he could generate more as needed.
Then he began forming the seals slowly, shaping two water vortices inside his mouth.
One vortex rotated left.
The other rotated right.
He controlled them, guiding both vortices toward the center. When they collided, the two spinning flows interlocked, like gears biting together, creating not only centrifugal pressure, but additional compression between the vortices.
Yoru felt the pressure spike instantly. A jet of water burst from his mouth, faster than ever before. It pierced straight through the first tree… and then embedded itself deep inside a second tree.
Maintaining chakra output, he swept the jet slightly sideways, the Severing Wave sliced clean through both massive trunks.
Success.
With a simple modification and knowledge from his previous life, he had created a far more powerful version of the technique.
He named the improved jutsu:
Water Style: Twin-Vortex Severing Wave.
After a dozen repetitions, he grew increasingly comfortable with it. He aimed the technique at a boulder. The water jet sliced the stone cleanly in half.
In actual combat, this would be his sharpest blade, a high-pressure water knife. For now, his exploration ended here. From this point on, it would take countless hours of polishing the technique, improving proficiency, lowering chakra cost, increasing power, refining hand-seals.
Hand-seals weren't just about the fingers, they required training the corresponding chakra pathways to increase seal speed.
Yoru remembered: in the original story, Fukasaku the Sage used a similar technique to slice through one of Pain's summoned beasts.
If he could reach that level of power, this jutsu would be terrifying.
Incredible speed, line-cutting range large enough to split the battlefield, definitely worthy of a Jōnin-class signature technique.
The Next Day
In the afternoon, Yoru received a mission:
Security detail for the Jōnin Assembly.
A very easy assignment. Who would be stupid enough to attack a gathering full of elite Jōnin?
ANBU mostly stood as the Hokage's background, transmitted orders, delivered scrolls, or summoned specific shinobi to speak. On the second floor of the Hokage Building, all ninety-plus non-frontline Jōnin were present.
Yoru stood in a corner performing the dullest guard duty imaginable.
On the front platform sat:
Hiruzen Sarutobi
Danzo Shimura
Koharu Utatane
The head of the Jōnin Corps, Shikakuro Nara, patriarch of the Nara Clan, said:
"All Jōnin have heard the news: The Hidden Sand Village has declared war on Konoha. Today's assembly will announce the commander, deputy commander, and division captains for the Wind River front…"
"Wait."
Yoru perked up instantly.
Someone dared interrupt the Jōnin Corps captain?
Seeing that it was Tsunade, he was no longer surprised.
Sitting in the front row, Tsunade rose and said:
"Before we talk about the Wind River front, shouldn't we first address the failures in the Hidden Grass and Hidden Rain war? Too many Konoha shinobi died there. Does no one think we should reflect, or take responsibility?"
All eyes turned toward the leadership on the platform.
Yoru admired Tsunade's courage, but felt her approach was too direct, likely ineffective against the elders.
As expected, Shikaku replied:
"The losses in the Hidden Grass and Hidden Rain war grieve us deeply. However, according to Commander Mitokado Homura's reports, we repelled the Hidden Stone Village forces from the Hidden Grass Village and secured agreement with the Daimyō.
From now on, the Land of Grass's Guardian Ninja will be selected from Konoha, and we will receive a share of their mission assignments. For the village, sacrifice is inevitable."
It sounded noble, "for the village", a phrase designed to shut down dissent. But Tsunade wasn't convinced anymore.
She continued:
"I proposed assigning one medical-ninja to each squad. With a medic, casualties drop drastically. If every squad can't have one, then double the number of frontline medics. Why hasn't the village done something so obviously correct?
Sacrifice for Konoha, I never hesitated. But there must be a limit. Why not reduce avoidable deaths?"
Koharu, responsible for internal affairs, was forced to respond:
"Princess Tsunade… training a medical ninja takes years. Anatomy, medical theory, medical ninjutsu, no Genin can master these in under five years. The medical-theory scrolls alone fill an entire cart.
The village understands the importance of medics, but the investment is too high and the timeline too long, impossible during wartime. After this war, I will listen to your proposals."
She didn't say it directly, but everyone understood:
Healing one injured shinobi costs far more than training a new expendable one.
Genin as disposable units. Chūnin as small-squad captains, also expendable. A coldly efficient war machine.
Many clan Jōnin nodded, they supported the system. But the civilian Jōnin, those who survived death-filled missions through grit and luck, looked deeply pained.
At that moment, the head of the Senju clan, Hanaki Senju, who also directed Konoha Hospital, stood.
She said:
"Lord Hokage, the Senju Clan has 227 shinobi. We are willing to devote our clan's strength to medical service, to treat the wounded. Our clan's unique physique allows us to learn medical ninjutsu easily.
We already have 112 medical-ninja. Among the remaining 114, Tsunade and I are confident we can train at least 50 more within one month."
The entire assembly turned toward Tsunade and Hanaki Senju, stunned.
What were the Senju planning?
They were using medical assignment as a reason to withdraw most clan members from combat duty.
Leaving the front lines… fully entering the medical system?
Yet to avoid criticism, they still kept 64 combat shinobi in the field.
They spent resources training medics for the village. They kept fighters for the village. In every way, the Senju appeared beyond reproach.
When women take charge, Yoru thought, they go for what hurts the most.