One thing really did keep another in check.
The scarlet Sharingan stared brightly, its single tomoe spinning around the pupil with excited energy. Konome watched the multi-eyed flesh sphere in her hands, the thing practically radiating malice, and couldn't help but marvel.
She still remembered how arrogant Hashirama's cells had been, how wildly they'd devoured her cells and chakra.
Yet the moment they met the Sharingan, they were completely suppressed by its ocular power. Not only could they not consume the Sharingan's strength, even their own chakra, so full of life, was being drawn out and absorbed in reverse.
"Ahh… ahh!"
The man's chest cavity gaped open, exposing a twitching heart and organs. He was still howling, but his tongue had been bitten off down to a half-stump, making his words unintelligible.
Konome found him too noisy.
She casually grabbed a rag and stuffed it into his mouth.
Pop.
Her semi-translucent nails avoided the arteries. Wrapped in a chakra scalpel, her hand drew a precise cut across his heart.
"Mmmph…!"
His bloodshot eyes rolled back from the pain.
Konome didn't even blink.
She split the heart open and embedded the flesh sphere into the wound. The green glow of medical ninjutsu lit the entire chest.
The pale sphere sprouted fleshy buds, fusing rapidly with the heart.
A normal chakra core, blue as clear sky, began seeping into Hashirama's glowing green core. The two started to infiltrate and merge, while the tomoe within the Sharingan spun like mad.
This man had been the leader of the three Kumogakure jōnin sent to smash through Konoha's front gate.
After they killed Kotetsu Hagane and Izumo Kamizuki, the other two jōnin were beaten to death by the reinforcements that arrived. This one tried to commit suicide, failed, and was captured alive with sealing jutsu.
The interrogation unit worked him for nearly two months, and he never opened his mouth. He even bit his own tongue to ruin his speech.
In the end, they could only break his will through torture, then pry into his brain with mental techniques to extract the intel. After that, he was thrown into Konoha's prison.
Somehow, Root got their hands on him and turned him into experimental material.
The green light swelled.
The wound sealed itself quickly.
Inside that blood-red heart, a pale patch of cells embedded with Sharingan began spreading outward. Konome immediately guided the man's own vitality to resist Hashirama's cells' invasion.
Crunch.
Behind her, Chihaya Tōru took a massive bite out of his apple, his sunken cheeks puffing out. As he watched Konome's calm, precise movements, admiration seeped from his eyes like juice from fruit.
After a month of teaching, he couldn't have been more satisfied with this assistant.
No matter how difficult the medical technique, she learned it once and mastered it fast. Any medical text he handed her, she finished in two days, memorized it, then applied it proficiently the day after.
Once upon a time, Yakushi Nono had been the most gifted person he'd ever seen. Every time he looked at the useless trash in the lab, he missed that former student.
Now it was different.
Danzo had handed him an assistant even more talented than Nono, and many of Root's experiments were now handled by Konome. Chihaya Tōru only needed to provide theory and direction.
Life had become dramatically easier.
With his daily chakra expenditure reduced, he even felt like he'd gained weight.
Living frugally made you adaptable. Living comfortably made you soft.
He only hoped this student lived long enough. He could barely imagine life without her anymore.
Tap. Tap.
The familiar sound of a cane came from outside the door.
"Danzo-sama!"
The respectful greeting from the staff exposed the newcomer's identity.
Click.
The operating room door opened directly. Chihaya Tōru tossed the rest of his apple into the trash and stood to greet him.
"Danzo-sa…"
An elderly man with a bandage over his right eye stepped in, cane in hand. He lifted one palm, cutting off Chihaya Tōru's fawning greeting with a single gesture.
Danzo's narrow left eye softened into a pleased squint as he watched the busy figure at the operating table.
"My disciple. How is she doing?"
"Flawless," Chihaya Tōru said, shaking his head in amazement. For a rigorous researcher to use the word flawless at all spoke volumes.
"Her chakra scalpel and Mystical Palm Technique are on my level. Ninety percent of the surgeries can be done independently. If she applied to Konoha Hospital as a department head right now, she'd qualify."
"And mentally? Any resistance?" Danzo asked.
In talent, Konome had never disappointed him.
He'd offered only two guarded lessons, and her Wind Release had surged by leaps and bounds. From that moment, he understood why someone so young could possess such strength.
Two hundred and fifty kilos of weight.
Two hundred and forty kilos of it was talent.
Chihaya Tōru was about to answer when the operating table suddenly shook violently.
"Mmmph!"
The man's body convulsed like a fish on a hook, making the table screech.
The skin over his chest was quickly healed under Konome's medical ninjutsu. But the moment her chakra paused, the pale Hashirama cells surged out and spread to the surface.
Dark skin was swallowed by whiteness.
In an instant, his entire chest was infected.
Konome narrowed her eyes.
At this rate, the man clearly couldn't withstand Hashirama's cells. Even with Sharingan suppression, he was only waiting to die.
If she let Hashirama's cells keep growing, those three single-tomoe Sharingan would be wasted.
Her chakra scalpel flashed, slicing his chest open again. Konome seized the heart, already fully overtaken by Hashirama cells, and ripped it out in one motion.
Rip.
Blood vessels like tree roots stretched and tore.
"Mmmph!"
The man's body jerked upward, hands clawing wildly at the metal edges of the bed.
A single sweep of the chakra scalpel severed the vessels. Only when the heart was completely removed did the man twitch twice and go still.
"There. Look," Chihaya Tōru said, smiling, presenting Konome with an open palm.
Konome placed the heart back into the culture dish, calmly removed her gloves, and showed not a flicker of emotion. She looked like a beautiful puppet carved from wood.
Chihaya Tōru didn't need to add anything.
This was exactly what Danzo wanted, almost to an excessive degree.
Danzo vaguely remembered. She was supposed to be a Konoha hero, the girl who'd fought a Kumo shinobi to save countless classmates.
Was Kotoamatsukami really that overwhelming?
Or had she finally revealed her true nature?
Why did her experimentation feel even more ruthless than Orochimaru's?
Ignoring Danzo and Chihaya Tōru's strange looks, Konome held the culture dish and carefully examined the flesh inside.
After devouring the man's energy, Hashirama's cells had grown significantly.
The mass now looked almost as large as an adult man's fist. Its chakra core had expanded too, producing more chakra.
The Sharingan embedded in the flesh had become even more crimson. They were starting to struggle to suppress Hashirama's cells, so they drank its chakra more frantically, converting it into ocular power.
One of the single tomoe spun so quickly it became a complete ring.
And as the accumulated ocular power deepened, a second tomoe slowly began to form within that ring.
"It evolved!" Chihaya Tōru blurted, unable to hide his excitement.
He didn't even bother pretending loyalty in front of Danzo anymore. He jogged over to observe the Sharingan's advancement with Konome.
"Yang really is the growth source of Yin," Konome murmured.
Her lips curled, unable to conceal her exhilaration.
Using the linkage between a Sage Body and the Sharingan, she had finally understood the relationship between Yin and Yang within the human body.
The most fundamental power in the body was Yang.
Yin, that versatile and all-purpose force, was the product of absorbing Yang and transforming it.
Souls, spiritual force, ocular techniques, all of it was nourished by Yang.
That meant people with powerful vitality never had weak souls. Instead, those born with abnormally strong souls often became physically frail because they absorbed too much Yang.
Uchiha Itachi's illness might have come from exactly that.
A Sage Body filled with endless Yang was the foundation of all of Ōtsutsuki Kaguya's power.
A heavy Gray Bone soaked in death could only be carried by a Sage Body with limitless life.
Massive Tailed Beast chakra required a Sage Body with equally massive chakra to seal it.
The Mangekyō Sharingan, bizarre as a wishing machine and terrifyingly versatile, needed a Sage Body to replenish ocular power and relieve the strain.
Madara Uchiha understood this clearly.
He stole Hashirama's chakra and awakened the Rinnegan, yes, but he lacked the vitality to support it. It took decades to barely nurture it, and by then he was already a withered husk.
Afterward, he implanted the Rinnegan into Nagato, who possessed the vitality of an Uzumaki, precisely to let that undernourished Rinnegan grow mature again.
And if Konome's instincts were right…
The Byakugan and a Sage Body had to have a linkage too.
Maybe the Yang of a Sage Body could be absorbed by the Byakugan and force it to evolve.
The Byakugan's control over flesh and chakra was terrifyingly precise. Maybe that was the point. To control active cells at the microscopic level, preventing reckless devouring and restraining the infinite conversion of Yang Release chakra.
Konome's eyes brightened.
The Sharingan's ocular power inside the Hashirama cells gradually stabilized. Two tomoe slowed and settled, locked in perfect opposition at one hundred eighty degrees, reflecting a cold scarlet sheen.
It clicked.
Everything clicked.
It felt like fog peeling away from in front of her eyes.
The world suddenly revealed colors she'd never been able to see.
Two dōjutsu. Two constitutions. Nine Tailed Beasts. A web of bloodlines. Yin and Yang.
The relationships behind Ōtsutsuki Kaguya's abilities untangled in her mind, one after another.
The so-called Progenitor of Chakra no longer held secrets from her.
"Why didn't the Sharingan I implanted before change like this?" Chihaya Tōru circled the culture dish, his expression slipping into a hint of madness.
"Because the earlier method of connecting the Sharingan to Hashirama's cells was too crude," Konome answered, still studying the dish.
"The synapses inside the optic nerve weren't fully repaired, and the blood vessels were still blocked. The eye couldn't absorb enough Yang."
With the Byakugan's microscopic sight, she could detect even the tiniest obstruction in those nerves and repair it immediately. That precision was what made the evolution possible.
Danzo had been ignored for so long he might as well not have existed.
Yet as he watched two mad scientists whirl around a glass dish, treating him like air, he didn't get angry.
He didn't care about their theories. He couldn't understand them anyway.
But he understood the result.
Konome had found a way to use Hashirama's cells to cultivate a single-tomoe Sharingan into a double-tomoe.
That meant all those single and double tomoe eyes had a chance to become three-tomoe.
And perhaps, with Hashirama's cells, even ordinary Sharingan could be nurtured into Mangekyō.
Hashirama's cells had always been a bottomless pit. Endless bodies consumed, almost no meaningful results.
Danzo had wanted to stop Chihaya Tōru's research long ago. Only stubborn unwillingness made him keep it going.
But if Hashirama's cells could evolve the Sharingan, everything changed.
Did he have many Sharingan?
Not limitless, but he could produce over a hundred.
If he handed them all to Konome and had her cultivate them into Mangekyō…
Who in the shinobi world could stand against him?
Danzo licked his lips, starving. His excitement surged even higher than theirs.
While Konome and Chihaya Tōru debated with rising passion, Danzo quietly sat down in Chihaya Tōru's chair, rested his cane across his legs, and made sure it didn't make a sound that might disrupt their inspiration.
Drip.
Drip.
Blood seeped from the dead man's open chest, sliding off the edge of the operating table and splattering the floor in radial stains.
Konome and Chihaya Tōru fed Hashirama's cells with chakra, then used medical ninjutsu to stimulate the other two Sharingan, trying to reproduce the phenomenon.
The gloomy old man leaned back, the fork-shaped scar under his chin relaxing as his one visible eye narrowed into a thin slit, fixed on Konome.
No one knew what he was thinking.
As the thick blood stretched into dark strings between table and tile, Konome and Chihaya Tōru finally grasped the key.
They successfully catalyzed the other two Sharingan into double-tomoe as well.
"It's all about the Sharingan's absorption efficiency," Chihaya Tōru said hoarsely, eyes bulging as he cradled the culture dish and stared into three crimson eyes.
"Konome, you're a genius!"
He had once worked with Orochimaru in pursuit of immortality, and they had split because their philosophies diverged.
Orochimaru believed that if the soul escaped the shackles of flesh, immortality would be achieved.
Chihaya Tōru believed immortality depended on absolute Yang power.
Now Konome's experiment proved neither of them was wrong.
Yin and Yang looked opposed, yet they were born from the same root.
A soul could invade another body and absorb Yang.
A body could generate endless vitality to nourish the soul.
Two roads. Both viable.
"Cough. Cough."
After sitting in silence for so long, Danzo finally cleared his throat to remind them he existed.
"Danzo-sama… you're still here?" Chihaya Tōru forced the culture dish down and offered a polite smile.
"Are you trying to chase me out?" Danzo snorted.
"I wouldn't dare."
Danzo understood his temperament and couldn't be bothered dealing with a man who forgot death the moment he started experimenting. He turned to Konome, whose mind was still racing, and gave a stiff smile.
"Well done. As expected of my disciple."
Chihaya Tōru's mouth twitched internally.
What does that have to do with you? I'm the one teaching her.
But he kept his head lowered and said nothing.
"Teacher, is there something you need?" Konome asked, absentmindedly, her thoughts blazing with Yin-Yang balance and transformation.
"If we can control the extreme Yin chakra inside the Sharingan and imitate the filtering layer on Hashirama's cells…"
"Could we purify vitality directly?"
It felt possible.
Pure Yin wasn't the answer. Pure Yang wasn't either.
Only by combining them could you evolve all things.
The most critical step of the Reverse Eight Gates might be right here.
"The experimental work can be handed to Chihaya for now," Danzo said, cutting through Konome's momentum without mercy.
"But I have a mission for you."
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