"Whew… it's been a long time since I've slept this well."
Inside the experimental base, Kurogane Ren stretched lazily. Over the years, he had either been training ninjutsu or experimenting with it. He only rested when his body absolutely couldn't endure any longer. While that kind of rest wasn't ineffective, it was never sufficient.
Humming lightly, he walked toward the Uzumaki corpse he had selected. A burning intensity shone in his eyes.
At last, the body that had been preserved in a cultivation tank for years was taken out, dried, and placed onto a massive scroll engraved with intricate formulas.
This scroll served as an auxiliary array, capable of preventing most unexpected complications.
Standing before it, Kurogane Ren took a deep breath and formed hand seals. This time, he was using the technique on himself.
"Ninja Art—Demon Assimilation Technique!"
In the next instant, his hands pressed down onto the scroll. The corpse upon it instantly dissolved into a black liquid, surging toward him.
Sitting cross-legged on the scroll, Kurogane Ren watched the black liquid engulf him, his gaze unwavering.
At the same time, the formulas inscribed on the scroll seemed to come alive, crawling up his body.
Finally, when the last of the markings vanished from the scroll, Kurogane Ren opened his eyes.
He looked down at his naked body. Black markings covered his skin, surrounded by sealing inscriptions. This was not unexpected.
After washing himself thoroughly, he picked up the white bandages he had prepared and carefully wrapped them around the marks, layer by layer.
Perhaps Hiruko hadn't intended to wrap his entire body in bandages—but without them, the marks would be far too conspicuous. And this was only after fusing a single bloodline. If someone like Hiruko had already fused four, who knew what his body had become?
Once the bandaging was complete, Kurogane Ren looked at himself in the mirror. Since he had only fused one bloodline, the markings were limited, and he still appeared mostly normal.
Still, with a body like this, finding a suitable wife in Konoha would probably be impossible. From this moment on, his body carried secrets that could not be shared—not even with a spouse.
Fortunately, while he wasn't entirely uninterested in such matters, his desire to grow stronger far outweighed everything else.
Beauty only slowed progress.
That principle applied to everyone.
After getting dressed, excitement flickered in his eyes. The fusion was complete—now came the testing.
In truth, he could already feel the difference. Without even consciously extracting chakra, the sheer amount generated instinctively was something he had never imagined before.
Kurogane Ren quickly made his way to a training room, sat cross-legged, and began carefully sensing everything within his body.
Chakra = physical energy + spiritual energy.
He had never lacked spiritual energy—his deficiency had always been physical energy.
In the past, when he extracted chakra, his spiritual energy felt like a vast river, while his physical energy was nothing more than a narrow ditch. A slight miscalculation would completely drain it.
Now, however, the physical energy within him—while not exceeding that river—was at least on equal footing.
Compared to before, it had increased countless times.
His eyes snapped open.
At that moment, he could no longer suppress the joy surging within him. He threw his head back and laughed.
Finally… the flaw that had plagued him since he first began training had been resolved.
After a long while, he calmed himself and began analyzing his condition.
The Uzumaki bloodline was indeed powerful, but what surprised him most was that his spiritual energy could keep up with it. He had always known his mental strength wasn't weak, but he hadn't expected it to rival an Uzumaki physique.
Perhaps this was a unique trait of having lived two lives.
Now that his chakra problem was solved, it was time to consider what came next.
For him, chakra quantity had been the most urgent issue—but the Uzumaki bloodline offered far more than just that.
It possessed at least three notable abilities.
First, a bloodline-specific sealing technique: Adamantine Sealing Chains.
Second, sensory abilities surpassing even the Byakugan: the Kagura Mind's Eye.
Third, a regenerative constitution—others could recover injuries and chakra by consuming their blood.
The third one required no further thought. Not all Uzumaki possessed it, and Kurogane Ren had already confirmed that his chosen subject did not.
He didn't particularly want it either. He could already use medical ninjutsu, and that ability was essentially trading one's lifespan for recovery. Overuse would accelerate death. Worse, it would make him a target.
As for the Kagura Mind's Eye, its sensing range was vast. It could even roughly determine a person's intentions—whether they were lying or harbored ill will. In many ways, it surpassed the Byakugan, which only excelled at visualizing chakra flow.
However, like the regenerative ability, it wasn't universal among the Uzumaki. It required innate sensory talent.
Kurogane Ren resolved to further develop his sensory abilities. If he could awaken the Kagura Mind's Eye, he wouldn't need to learn any other detection techniques.
Finally, the Adamantine Sealing Chains…
Those were not difficult.
Kurogane Ren had become a Special Jonin largely due to his proficiency in sealing techniques. The formulas inscribed on his scrolls were all personally crafted. Thus, he quickly sensed the sealing power within his new bloodline.
He attempted to draw upon it.
Almost instantly, golden chains burst forth from his back, dancing through the training room.
This was the Adamantine Sealing Chains—the unique sealing power of the Uzumaki bloodline.
Unlike most techniques, it required no external formulas to use. Just as Karin, despite lacking formal Uzumaki training, could unleash it instinctively in moments of crisis.
That said…
It was far too conspicuous.
The moment he used it, his Uzumaki heritage would be exposed. Unless absolutely necessary, it was better avoided.
Still, even if it were exposed, it wouldn't be entirely unreasonable. After all, he was a Konoha ninja, and the Uzumaki and Konoha had once been closely allied, with intermarriage not uncommon.
Even if Konoha had records on him, they would never be as detailed as those in his previous life.
So his sudden display of Uzumaki bloodline traits wouldn't be entirely suspicious.
It could even explain his sudden surge in chakra—his Uzumaki lineage had simply awakened after years of dormancy.
As these thoughts settled, Kurogane Ren smiled and stretched lazily.
As for being exposed…
He'd deal with that when the time came.