Time flew by in a blur—half a year had already passed.
Throughout that time, Tahara Rokuro had been immersed entirely in experimentation. As for missions, he left them all to Hyūga Hizashi and his shadow clones.
Of course, due to range limitations, Hizashi only accepted assignments that could be done within or near the village—no more border patrols or long-distance deployments.
Because of this, he had drawn quite a bit of criticism from the Hyūga Main Branch.
After all, Hizashi was considered the strongest among the Hyūga Branch family. Many Main Branch members preferred having him as their escort during outside missions.
Now that he refused long-distance assignments, complaints were inevitable.
Still, being Hyūga Hiashi's younger brother, no one dared go too far as long as Hiashi remained clan head.
After six months of tireless effort, Rokuro's Tenseigan Project had finally reached the moment of truth.
The three of them—Rokuro, Uchiha Kei, and Uchiha Ashikaga—each had dark circles under their eyes, greasy hair, and an unmistakable stench that spoke of sleepless nights and skipped baths. For people living in a Japan-based shinobi world, this was borderline torture.
"At last… the final step. Whether it succeeds or fails—all depends on this shot."
Rokuro held a syringe filled with a dark violet liquid, his expression grave. Then, he injected it into a white rat—no ordinary one, but a creature the size of a grown rabbit.
Yes, this "rat" was the result of dozens of previous enhancements—technically still a rat, yet no longer truly one.
Rokuro had used every bit of Orochimaru's body modification techniques on it. He had even dissected the white-scaled serpent he'd acquired earlier, completely mastering Orochimaru's art of soft-body reconstruction.
"This thing's strength could probably rival a water buffalo's by now."
He glanced at a twisted, half-shattered iron cage nearby. The bars, each as thick as a thumb, should have been strong enough to contain even a bull. Yet two days ago, this same rat had effortlessly crushed the cage and escaped.
If not for Rokuro's quick reaction—activating his Adamantine Seal to subdue it—months of work would have gone up in smoke.
As the gene serum entered its system, the rat's fur stood on end. When the last drop was injected, it let out a deep, guttural roar more fitting for a tiger or leopard.
"Everyone, move!"
All three began using medical ninjutsu simultaneously, flooding the rat with chakra to accelerate the fusion process.
Under the glow of vibrant green light, the rat's body swelled—doubling in size until it was as large as a farm dog.
Then came the most astonishing discovery—its body emitted clear chakra readings.
"Success! It's… it's become a ninja beast!"
Uchiha Kei activated her Sharingan to observe. While the dōjutsu couldn't see through the body's network of chakra channels, it could still sense chakra flows with great precision.
Under her gaze, the rat's chakra climbed rapidly—reaching Genin-level capacity in minutes, enough to unleash several Fireball Jutsu with ease.
And it wasn't stopping there.
As the fusion deepened, its chakra output surged even higher, reaching Chūnin-level in just half an hour.
"Grrraaaaah!"
The rat roared, attempting to lash out, but Rokuro quickly tightened the chakra chains binding it, locking it to the operating table.
"We're so close to success. This time—it's going to work!"
Months of effort were about to pay off. The three continued pouring chakra into their medical jutsu, quickening the fusion further.
Two more hours passed. The rat's chakra reserves had now reached Jōnin-level, and what came next made their eyes widen in disbelief
Its chakra began manifesting externally, forming a visible layer of energy—akin to the Lightning Release Armor or a tailed beast cloak.
"That's chakra form manipulation! But… what nature is it?"
Uchiha Ashikaga's jaw dropped. After all, even the basic Three Body Techniques—Clone, Substitution, and Transformation—were considered foundational chakra control exercises for Genin-level shinobi.
Yet here was a rat—displaying chakra control beyond most Genin!
"Its chakra's still rising… Is that really safe?"
Kei's Sharingan spun faster, sensing the unstable energy swelling within.
Rokuro, however, looked thrilled.
"This is how it should be! If a perfected Byakugan only grants Jōnin-level chakra, then the entire Tenseigan experiment would be meaningless!"
Kei thought about it and nodded. Indeed, raw chakra volume alone didn't make one a Jōnin—control, nature transformation, and form manipulation all mattered.
"Rokuro, if this keeps up, won't its chakra reach the Kage level? Maybe even Hiruzen's?"
Before Rokuro could answer, the rat's chakra exploded exponentially, soaring to Kage-class in mere seconds.
Its chakra output had now surpassed Sarutobi Hiruzen himself—and it was still climbing.
In Rokuro's eyes, it was rapidly approaching the same chakra density as the mini Nine-Tails he'd once sealed—a tenth of the real Kyūbi's power. The discovery left him trembling with excitement.
For months, he'd been forced to act low-key after the little Nine-Tails had self-destructed, robbing him of his "chakra battery." Without it, he could no longer spam techniques like Shinra Tensei and Banshō Ten'in freely.
Now, he might finally have a substitute.
But just as he smiled
Crack.
A faint snapping sound came from the chakra chains.
"Not good! Get back!"
Rokuro shouted, pulling his mother and Kei backward while simultaneously reactivating the Adamantine Sealing Chains, now fully engaging their chakra absorption mode.
Yet
Crack. Crack-crack!
The sound grew louder. The chains fractured one by one—until finally, one snapped completely.
"What?! It's not absorbing its chakra?!"
Rokuro's face paled.
The rat threw its head back and unleashed a roar that shook the ground—a sound no smaller than a tailed beast's cry.
CLANG!
With a deafening metallic crash, all the chakra chains shattered. The Adamantine Seal was destroyed.
The creature—now fully engulfed in roaring chakra—lunged at Rokuro like a cannonball.
A flash of gold. Rokuro grabbed the two women and vanished using the Flying Thunder God Technique, reappearing outside the underground lab.
BOOM!
The explosion tore the ground apart, blowing a massive crater through the lab.
Trees for dozens of meters around were flung into the air—the blast power on par with a Tailed Beast Bomb.
And then they saw it.
The "rat" had grown to the size of an elephant.
This was no longer a lab specimen—it was a monster.
With another thunderous roar, the giant white beast charged at them, its claw sweeping down like a guillotine.
Rokuro raised his hand calmly.
"Shinra Tensei."
END OF CHAPTER
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