Chapter 357: Intelligence on the Tenseigan (Double Length Chapter)
What Shisui was thinking—or what he chose to do—was something Kei had no way of knowing.
What he did know, however, was that he had stumbled upon something genuinely fascinating.
Something extremely interesting.
His right eye had suffered severe strain—very severe.
When he combined Susanoo with that single slash, his ocular power had already been pushed close to its limit, causing blood to spill from both eyes.
After that, in order to test one of his hypotheses, he had once again activated Chrono Drift, forcibly undoing his own expenditure.
The result was acceptable.
But that reversal did nothing for his mental fatigue—and did nothing to help his right eye.
However, after resting properly for an entire afternoon, he conducted what he had planned to be his final experiment inside the laboratory.
That was—
Using the ability of his left eye to accelerate the recovery of his right eye.
This was an experiment he had wanted to perform for a long time, but previously had no way of attempting.
It wasn't that he had never considered using his left eye's ability to accelerate processes.
For example, his triple-cell fusion experiment.
If he could speed that up, the pace of his growth would increase dramatically.
But the obstacles were overwhelming.
In the past, ocular power itself had been the primary limitation.
Secondly—and more importantly—he had no guarantee that it would even work.
He would need to precisely locate specific cells within his body and then control them through ocular techniques.
Without the Byakugan, that was simply impossible.
Now, however, his strength had increased.
While he still couldn't precisely identify individual cells, he had at least crossed the first threshold—the restriction imposed by ocular power.
That alone made experimentation possible.
So, after resting sufficiently, Kei proceeded with his final test.
And the result left him extremely satisfied.
Under his precise control, the ocular power of his left eye was directly applied to his right eye.
The acceleration lasted for roughly one minute.
Before discomfort began to set in, he stopped.
His right eye hadn't fully recovered—but it had reached a state where combat was once again possible.
This experiment could only be described as groundbreaking.
From this point on, the development of his ocular abilities would accelerate dramatically.
Even though these experiments hadn't involved direct combat—
Even though their effects were mostly indirect—
Their value, both in expanding the application of his abilities and in self-support, was immeasurable.
For example—
"What exactly did you do?"
Kenta stared at himself in shock, while Ayaka had already activated her Byakugan, her face filled with disbelief as she observed what was happening.
Both of them were inside the laboratory.
Unlike Ayaka—who had accompanied Kei to the canyon that morning and personally witnessed that horrifying slash—
Kenta had only arrived after receiving a summons.
The moment he arrived, Kei told him they were going to conduct an experiment.
Naturally, Kenta was confused.
He asked what kind of experiment it was.
Kei's answer, however, was vague.
He simply said he wanted to try accelerating Kenta's fusion progress.
Kei couldn't control cells directly.
So he changed his approach.
Instead, he attempted to control the highly active, boiling blood, or the serum that had been injected into Kenta's body.
Although Kenta wasn't scheduled for a full reinjection yet, introducing a small amount of serum was still acceptable.
Under Ayaka's supervision and assistance, Kenta finally agreed.
The result stunned both of them.
The serum erupted with an unprecedented level of activity once it entered his body.
That activity dramatically accelerated its dilution—and greatly hastened the fusion process.
Of course, such extreme acceleration caused Kenta to suffer negative reactions once again.
Even worse, the energy that had previously accumulated due to his slower fusion rate also became active.
"How should I put it…"
Kei spoke with his left eye closed.
"I only tried accelerating the dilution of the serum inside your body. The effect seems decent—but the cost and strain are huge. And since this was my first time controlling it, the execution wasn't very refined."
He deliberately kept his explanation vague.
Not because the process wasn't astonishing—but because saying too much would only make it harder to manage the consequences.
Some things were better handled conservatively.
Even so, both Kenta and Ayaka fell silent.
Even this "conservative" explanation was already unbelievable.
"When did you master this?" Ayaka asked cautiously.
"Was it earlier… or only today?"
"You saw it yourself," Kei tilted his head slightly.
"I've had the ability for a while. But for certain reasons, I couldn't use it. Even if I knew it was possible, I wasn't willing to risk damaging my eyes."
"Now your power has crossed a threshold," Kenta said, his face pale as he clenched his fist unconsciously.
"So you don't have to worry about your eyes anymore… which is why you dared to use it."
"Even though you used me as an experiment," he continued,
"you still sped up my fusion. This ability is really…"
Ayaka ignored him.
"Can you maintain this technique for long periods?" she asked instead.
"And can you precisely locate cells? Accelerating serum activity like this is far too crude."
She was absolutely right.
This method carried serious side effects.
The only reason this experiment worked as well as it did was because the dosage was small—and because Kenta had already undergone many rounds of fusion.
Even so, the serum's activity had been pushed to the extreme.
Kenta's face was ghostly pale.
The chaos in his chakra alone made it clear how intense the effect had been.
Results aside, he could barely stand.
If recovery took too long, the time cost might outweigh the benefits.
"I don't have a solution for that yet," Kei sighed.
"The Sharingan isn't the Byakugan. To be honest, at this stage, the Byakugan's auxiliary capabilities are incredibly strong—far beyond what the Sharingan can replicate.
"I can't precisely locate cells like you can. Even with your assistance, it wouldn't necessarily work."
"What a waste," Ayaka muttered, clearly disappointed.
"You have such an incredible ability, yet you can't use it the way we need."
"There's one thing you're mistaken about," Kei said, raising an eyebrow with a faint smile.
"It's not that I can't do what we want. The cost is simply too high."
"You can control cells?" Ayaka's eyes lit up—then she immediately frowned.
"No… you said before that you'd have to use a different method."
"Correct," Kei nodded.
"I could forcibly accelerate your entire body's functions. You might even experience what it feels like to reach adulthood instantly. Honestly, I'm kind of curious myself-"
"Pervert."
Ayaka snapped back instantly, cutting him off.
Kei froze.
What was wrong with adulthood?
Was his phrasing off?
He rubbed his chin, then shrugged it off.
His attention returned to Kenta.
"Ayaka, how's his condition?" Kei asked.
"Besides chakra, what else has improved?"
"The biggest change is his fusion rate—it's increased by about ten percent," Ayaka said coolly.
"That alone is unbelievable.
"He's now at roughly fifty-five percent fusion, and it's still stabilizing. As for how much power he can actually use—that depends on him."
"Is that so?" Kei nodded, then turned to Kenta.
"Then tell me—do you think you can use Wood Release now?"
"I'm not sure," Kenta hesitated.
"But I think it should be possible. I've tried before—though the quality was terrible. It was only good for… building houses."
Building houses?
For some reason, Kei immediately thought of Yamato.
He had no idea what Yamato's fusion rate was—or even where the guy currently was.
Was he in Minato's ANBU?
Or still serving under the Third Hokage's Root?
Who knew.
But at least now, Kei understood Kenta's situation.
If Kenta could already produce low-quality Wood Release before—
Then now, the improvement should be substantial.
This experiment also gave Kei far more confidence in his own control.
If he'd had this ability earlier, he might have even attempted to force-mature the Eternal Mangekyō.
But missed chances were missed chances.
His current state was already more than satisfactory.
And now, he had living proof to test further.
Kenta was just one case—promising, but still crude.
Ayaka, however, was far more interested.
She wanted Kei to help accelerate her growth as well.
And she had noticed something.
When Kei said,
"the Byakugan's auxiliary ability is extremely strong at this stage,"
that wording caught her attention immediately.
At this stage.
Which implied—
He knew what came next.
He had promised long ago to investigate these matters.
And now, he had accidentally revealed something he shouldn't have.
That could only mean one thing—
He had acquired new information.
Important information.
And Ayaka had no intention of letting it slide.
"This question surprised you?" Kei raised an eyebrow.
"But… yes. I do have some new intelligence.
"I didn't say anything earlier because there's still a lot of uncertainty."
"That doesn't matter," Ayaka said seriously.
"We're both walking an uncharted path. You're exploring ahead—so am I.
"Do you know where the road leads?"
"If you're uncertain, then so am I.
"And that's exactly why you should tell me."
Sorry—this one thing, I actually do know.
Kei thought this silently to himself.
He had always known where the road ahead led.
Although what he was doing looked like experimentation—like exploration—he could judge exactly how far he had progressed from the results alone.
In truth, Kei's path was not something he was blindly feeling his way through.
He had a clear benchmark.
A definite reference point.
Ayaka had misunderstood that completely.
Of course, he had no intention of explaining any of this.
What he was considering, however, was how to explain the matter of Byakugan evolution to her—and how much to explain.
Kei did feel that it was time to reveal something.
But what to reveal, how deeply to go, and to what extent—those were things that required careful thought.
In the original records, the evolution of the Byakugan could almost be described as nonexistent.
A perfectly ordinary-looking Byakugan—one that didn't even appear to enhance combat ability—
somehow transformed directly into the Tenseigan.
And then came the Tenseigan Chakra Mode.
That mode was absurdly powerful—so powerful it bordered on the unreasonable.
Because in that state, the user could even wield Truth-Seeking Orbs.
Of course, Kei wasn't entirely certain those black spheres truly were Truth-Seeking Orbs.
After all, he knew very well how those things were supposed to be formed.
They required mastery over all five elemental natures plus Yin and Yang Release—
in simple terms, the fusion of all chakra transformations.
Did awakening the Tenseigan automatically grant access to every chakra nature?
Kei wasn't sure.
And precisely because he understood this uncertainty, he had never neglected the completion of his own chakra attributes while improving his strength.
Wind Release was the one element he had only recently begun to grasp—
something he had cultivated entirely on his own.
It was weak.
But with continued training and refinement, it would be usable in real combat without issue.
Fire Release was innate to him.
Lightning Release came naturally as well.
Earth and Water Release were completed through White Zetsu cells—
not frequently used, but fully serviceable.
Yin Release was inherent to the Sharingan, and his mastery of it was exceptional.
Yang Release, once again, was something he owed to White Zetsu cells.
At this point, although the strength of his various chakra natures differed significantly,
Kei had, in a sense, completed the set.
But precisely because of those imbalances, he dared not recklessly attempt chakra fusion—
trying to create something like Truth-Seeking Orbs or ultra-high-level ninjutsu.
Combining chakra natures was never simple.
If it were, successful results wouldn't be classified as Kekkei Genkai.
Two-nature fusion was already difficult.
Three-nature fusion—the realm of Kekkei Tōta—was on an entirely different level.
In the entire ninja world, only that old man Ōnoki possessed such an ability.
Kei had no intention, for now, of pursuing anything like a Kekkei Mōra.
Truth-Seeking Orbs were appealing, yes—
But with his current imbalance, he was far more likely to blow himself up.
Shaking his head, Kei brought his thoughts back to the present.
Truth-Seeking Orbs were too distant a goal.
He hadn't even fully stabilized the Eternal Mangekyō yet.
His chakra refinement still required time.
Everything had to be taken one step at a time.
As for whether the black spheres in Tenseigan Chakra Mode were truly Truth-Seeking Orbs—
That honestly had nothing to do with him.
At most, he could remind Ayaka to be mindful of that direction.
Beyond that, there wasn't much he could do.
"Alright," Kei finally said aloud.
"I should just tell you directly."
"But the information I have comes from fragmented records—many of them incomplete.
They were compiled and categorized later, but the data itself is chaotic."
"That's fine," Ayaka replied without hesitation.
"I'm mentally prepared."
She sounded a little impatient, but given the importance of the subject, she understood his caution.
"Don't worry," she added.
"My mental resilience is far stronger than you think."
"That's good," Kei nodded.
"Being prepared is important."
After a brief pause, he began.
"According to scattered historical fragments, some people once witnessed your ancestors manifesting a different kind of eye."
"But those cases were extremely rare. For the most part, the Byakugan remained as it is now."
"However, there is a record of one Hyūga prodigy—a branch family member."
"Even when surrounded by twenty shinobi, all at least jōnin-level, he defeated every single one of them with pure taijutsu in under a minute."
Kei spoke calmly.
He wasn't exaggerating.
In his memory, there had been a Root operative from the Hyūga clan who had accomplished something that absurd.
A man who had effectively left the Hyūga due to inheriting a Byakugan only every other generation—
his name was Kohinata Mukai.
Kei wasn't even sure such a person existed in this world.
But the record of his feats?
That, Kei remembered clearly.
That man had once infiltrated the Kazekage's residence to eavesdrop on alliance talks with Kirigakure.
When his teammates made a mistake and blew their cover, he led them straight back to the Land of Fire—
And along the way, he killed twenty enemies alone in record time.
Even Uchiha Itachi and Uchiha Shisui had once been defeated by him together.
Of course, he died young.
How he died, or how Itachi and Shisui eventually turned the tables—Kei didn't know.
But that didn't matter.
Whether the story was true or embellished didn't concern him.
It was more than enough to serve as a reference.
He had even considered deliberately downplaying the concept of the Jōgan and presenting it as an attainable future goal for Ayaka.
If she eventually reached that point and discovered inconsistencies—
He could always say the records were flawed.
"That strong?" Ayaka frowned.
"That level would surpass even Hyūga Hiashi. You might manage it, but a branch family member?"
"There are no further records," Kei replied evenly.
"He seems to have died. No one knows how—it was too long ago."
"But there are accounts of someone even more terrifying."
"Even more exaggerated?" Ayaka felt as though she were listening to a myth.
If she didn't trust Kei completely, she would have thought he was lying.
A branch family member defeating twenty jōnin-level opponents in under a minute?
Titles didn't mean much, especially in ancient times.
Still, shinobi with jōnin-level chakra were never incompetent.
Killing that many in sixty seconds was absurd.
To Ayaka, the only person she knew who might manage such a feat was Kei himself.
Because she knew his speed.
She knew how terrifying his eyes were.
For him, it would be simple—maximum speed, one genjutsu, one strike.
But that Hyūga had done it with pure taijutsu.
"Yes," Kei said, nodding.
"And the most important detail is this—according to the records, his eyes were no longer the same as those of ordinary Hyūga."
"Different how?" Ayaka pressed.
"When he fought, his eyes transformed into something described as
'radiant azure, like stars scattered across the heavens.'"
Kei recalled the image of the Tenseigan, using the archaic phrasing found in the texts.
"Blue chakra enveloped his body. And—"
"And what?" Ayaka snapped.
"Don't stop halfway!"
"And like me now," Kei finished calmly,
"he possessed all chakra natures. His control was far superior to mine—otherwise, he could never have sustained such a chakra mode."
"…All chakra natures," Ayaka murmured.
"Brilliant blue eyes…"
She fell silent, absorbing the implications.