Deep beneath Root headquarters, in one of its most secret underground laboratories, faint footsteps echoed softly.
Uchiha Feiyu pushed open the heavy metal door and slipped inside like a ghost, his gaze sweeping over the busy researchers within.
Although Root's researchers were technically ninja, most of them were paper-pushers with little real combat experience. Talents like Orochimaru—or the Second Hokage—who could balance frontline combat and cutting-edge research were rare monsters, not the norm.
With Feiyu's Five-Senses Control genjutsu, controlling twenty or thirty ordinary researchers at once was effortless. This entire laboratory only had five researchers total, plus two Root guards.
In fact, it wasn't just this lab.
At this point, there were very few places within Root that Feiyu hadn't already "visited." To him, Root held almost no secrets anymore.
That included the plans of Konoha's upper echelon.
Feiyu already knew that Root had begun supplying Orochimaru with Uchiha test subjects. What no one knew, however, was that once those experiments were finished, the Uchiha corpses never stayed in Root's hands.
They all ended up with Feiyu.
Any Uchiha worth Orochimaru's attention naturally possessed three-tomoe Sharingan. Even after their eyes were harvested, the bodies alone were still extremely valuable.
More importantly, those corpses had also been injected with Hashirama Cells.
After tossing them into the Blood Pool, Feiyu could clearly feel his bloodline strengthening again.
The reason he'd been able to fuse Susanoo with Lightning Release Chakra Mode so smoothly was largely because his bloodline had advanced further. His Susanoo had already reached the muscle stage, placing his ocular power just one step away from true Mangekyō-level.
Yet strangely, his eyes themselves seemed firmly "locked" at the three-tomoe stage.
Even though his eye power had long surpassed what ordinary three-tomoe Sharingan should be capable of, there was no sign of actual evolution.
That wasn't necessarily a bad thing.
If Mangekyō manifested openly, both the Uchiha clan and Konoha's leadership would start having too many ideas.
Within the Uchiha, Mangekyō Sharingan was practically a sacred banner. Even if Feiyu was already stronger than most Mangekyō users, they would still fanatically believe in the supremacy of Mangekyō itself.
As for Konoha's higher-ups—having studied the Uchiha's awakening process—they regarded Mangekyō users as dangerous lunatics wielding doomsday weapons.
"Still no new Uchiha test subjects today?" Feiyu clicked his tongue. "Danzo really isn't pulling his weight."
"The clan has nearly a thousand ninja. Over two hundred have awakened Sharingan, and more than half of those are three-tomoe. And yet… only four experimental bodies so far."
After inspecting the lab, Feiyu let out a small sigh.
Getting Uchiha corpses was harder than it should've been.
If Danzo and the Third Hokage knew what Feiyu actually thought, they'd never imagine that using Uchiha experiments to drive a wedge between him and Orochimaru was a viable plan.
Feiyu felt absolutely no attachment to his so-called clansmen.
If anything, he was even greedier than Orochimaru—eyeing their bloodline like livestock, wishing he could pen the entire clan up and harvest them on a schedule.
"Well, no Uchiha bodies… but Hashirama Cells have grown nicely."
Feiyu strolled deeper into the lab, stopping in front of a massive cultivation tank roughly three meters across. Inside churned a grotesque flesh mass over two meters in diameter.
Most disturbing of all, countless faces resembling the First Hokage were embedded across its surface.
Even with their eyes closed, the sight alone made one's sanity wobble.
"I wonder how the First Hokage would feel seeing this," Feiyu muttered.
"Probably about the same as catching his best friend wearing his face on his chest."
With a quiet chuckle, Feiyu drew his blade and cleanly sliced the enormous flesh mass in two.
One portion contained nearly ninety percent of the cells. The other held the remaining ten.
He stored the larger portion away, leaving only a fraction behind in the tank.
Immediately, the lab erupted into noise.
"The cultivation unit's malfunctioning again! Wood Release cells are dying off!"
"Inject high-concentration nutrients! Add Compound No.13! Get two ninja in here—Earth and Water chakra, now!"
"Damn it, why does this keep happening?! It never used to!"
"Stop complaining and stabilize it!"
"Thank goodness Wood Release cells are resilient and invasive. As long as nutrients are sufficient, regrowth is easy. Otherwise we'd be bleeding resources every cycle!"
The researchers argued intensely, completely oblivious to Feiyu standing beside them—holding a massive chunk of Hashirama Cells.
Calmly, Feiyu sealed the cells into a storage scroll.
This marked his thirtieth harvest in six months.
Ever since discovering Root's Wood Release cultivation lab, he'd been coming by almost weekly. Fortunately, Hashirama Cells grew absurdly fast given enough nutrients—otherwise he would've stripped the entire facility bare long ago.
Thirty harvests later, Feiyu had accumulated nearly twenty tons of Hashirama Cells.
All of it was preparation for the Blood Pool.
Among all materials available to him, Hashirama Cells were easily the finest bloodline-evolution resource.
Even a fingernail-sized fragment could rapidly proliferate into a flesh mass several meters wide. And unlike most sacrifices, the quality didn't degrade with quantity.
Given enough volume, they were far more effective than sacrificing masses of ordinary ninja.
"The Blood Pool traces bloodlines comprehensively… but materials still matter."
"I wonder—if I throw this much Hashirama Cells into it… could I awaken a true Sage Body?"
With his current cultivation plateaued and no immediate breakthroughs in sight, Feiyu decided the time had come.
That very night, he left Konoha and descended into the underground cavern housing the Blood Pool, dumping all the Hashirama Cells inside.
Moments later, the Blood Pool finished refining them.
Brilliant crimson essence surfaced—small in volume, yet radiant like polished rubies, overflowing with vitality.
Feiyu stepped in and activated the Swallow-Spirit Blood-Refining Art.
In less than fifteen minutes, every last drop was absorbed.
When he tore free from the flesh cocoon and emerged, Feiyu clenched his fist.
His vitality had multiplied five or six times over.
His chakra reserves surged to several times that of an average Kage.
More unusually, his chakra now brimmed with pure life force—Yang Release refined beyond a critical threshold.
Stepping outside, Feiyu casually placed a hand against a tree and infused chakra.
The tree shuddered—and sprouted fresh buds.
"Tch… so this counts as Wood Release?"
"But this level's barely better than Yamato's landscaping skills."
Shaking his head, Feiyu abandoned the idea.
Wood Release was stronger than most kekkei genkai due to its Divine Tree origins—but it was far from invincible.
Hashirama Senju's dominance came from his boundless chakra and Sage Mode, not Wood Release alone.
Even with partial Sage Body traits awakened, Feiyu could tell—his Wood Release wasn't impressive.
"But if I keep refining Hashirama Cells… my Sage Body will keep improving."
"Eventually, I'll reach Hashirama's level."
"…Guess I should see if Root has any Wood Release jutsu scrolls."
Through repeated refinement cycles, Feiyu had begun to fully understand the Blood Pool's principles.
Chakra altered genetics. And the ultimate source of that alteration was the Ōtsutsuki.
The Blood Pool extracted the fragments closest to that origin—and refined them.
Naturally, there was a ceiling.
No refinement could surpass the bloodline's source.
All chakra traced back to Ōtsutsuki Kaguya. In theory, endless harvesting could approach her level—but in practice, chakra dissemination came from the Sage of Six Paths.
Reaching his brother's lineage would require harvesting the Hyūga for centuries.
In other words, Feiyu's refinement path could only ever approach the Sage of Six Paths.
As for Hashirama Cells—their ceiling was Hashirama himself.
"No shortcuts to becoming an Ōtsutsuki, huh."
As that fantasy died, Feiyu felt his ocular power surging too.
Something stirred—two distinct techniques slowly forming.
He touched his eyes, smiling.
"My eye power's almost at true Mangekyō level… or maybe even Eternal Mangekyō?"
"Didn't expect Hashirama Cells to aid Uchiha evolution—but it makes sense."
"The Uchiha inherited fragments of Sage Body… the Senju inherited fragments of Sage Eyes. Incomplete, but compatible."
Back in Konoha, Feiyu found himself oddly idle.
Further training wouldn't bring rapid gains. Root missions barely fed his magic-path progress.
"…I'd rather be on the battlefield."
He sighed. "Whatever. Let's see what Root wants."
The moment he reached Root's entrance, two operatives stepped forward.
"Uchiha Feiyu. Lord Danzo summons you."
"Tch. Another job?" Feiyu muttered. "Hope it's not too far."
They led him inside.
"Feiyu, you're here."
In the dim office, Danzo sat wrapped in bandages, cold and sinister as ever.
When Feiyu entered, the old man forced a smile onto his face.
It was deeply unsettling.
Feiyu resisted the urge to say please don't smile and instead asked bluntly:
"So—who am I killing?"
"Where?"
"And how many?"
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