A puff of white smoke rose from the scroll, and within it, a tall, thin figure gradually appeared—it was Kurogane Ren, who had just been inside Hiruko's experimental base.
He had long since placed multiple Summoning Technique scrolls in both his home and his experimental base. Whenever needed, he only had to signal a crow to open the scroll.
As for why he hadn't simply had the crow carry the scroll earlier, the reason was obvious—doing so would immediately expose it as a summoned creature.
Secondly, the scroll was enormous, nearly the size of the one Jiraiya carried. A crow simply couldn't handle that weight.
Kurogane Ren had considered going directly to his experimental base, but unfortunately, Konoha was constantly enveloped by a barrier. While it seemed useless at times, and he knew the entry and exit codes, using the Summoning Technique to bypass it would mean entering without identity verification. If he were mistaken for a spy, it would spell trouble.
So even when using summoning to travel to his base, he would never do so within Konoha's barrier.
As for Hiruko's experimental base? Naturally, it was inside the barrier.
Now back in his home, Kurogane Ren released the seal and looked at the pile of scrolls in front of him, each recording the research behind the Demon Assimilation Technique. A smile slowly spread across his face.
In the end, he couldn't help himself. Covering his forehead with one hand, he burst into laughter.
"Heh… hahahaha!"
"Finally… I've finally reached this point! The Demon Assimilation Technique!!"
Fortunately, there were few neighbors around his house. Otherwise, his laughter and shouting would have woken everyone nearby.
As the laughter subsided, Kurogane Ren stared at the scrolls with bloodshot eyes.
Though it was already late at night, there was no chance he could sleep in this state. He might as well… dive straight into it.
Meanwhile, back at Hiruko's experimental base, Hiruko himself walked in with a look of excitement still lingering on his face.
For years, he had experimented endlessly, yet he could never find a path to surpass the Sannin.
But now, not only had he gained inspiration from Kakashi Hatake's Sharingan, he had successfully implanted a puppet technique on him. All that remained was to wait for the right opportunity…
At the thought, a grin once again spread uncontrollably across his face.
As for the slight increase in humidity within the base, he didn't notice it at all. He didn't even bother checking whether his research records had been tampered with.
After calming down slightly, Hiruko began planning his next steps. Kakashi's Sharingan could wait—for now, a mere two-tomoe eye wasn't enough.
The Sharingan only truly displayed its power at three tomoe.
So next, he needed to find other bloodline limits.
Frowning, he considered his options. Aside from the Sharingan, the village also had the Byakugan…
At that very moment, news of Kakashi being attacked had already been discovered.
After all, Kakashi was currently Konoha's hero. Being assaulted while recovering from injuries was something the Hokage could not tolerate.
Thus, three individuals—ones Hiruko knew all too well—were dispatched. At this very moment, they were following the traces he left behind, heading straight toward the experimental base.
However, none of this had anything to do with Kurogane Ren anymore.
…
Back in that same shabby house.
Since obtaining the Demon Assimilation Technique, Kurogane Ren had not made a single move for several days. It almost seemed as though the house had been abandoned.
Yet inside, there sat a man who hadn't moved for a very long time—like a statue.
Kurogane Ren remained seated in the same position, clutching the experimental records. His face was now covered with stubble, and the whites of his eyes were filled with blood vessels from exhaustion.
Even so, his physical fatigue did nothing to dull his mental excitement.
His pupils remained sharp and focused as he continued studying the Demon Assimilation Technique.
During this time, he had also used the Clairvoyance Technique to observe Hiruko's base. As expected, Hiruko had not discovered anything.
Before long, he saw the arrival of the Sannin. From that, he could easily guess that Kakashi's situation had been exposed.
Even then, he forced himself to pause his research, directing his crows to observe from a safe distance. Only after confirming that their target was solely Hiruko did he finally relax.
He had genuinely feared they might discover his traces. While he had contingency plans to escape, such complications would severely disrupt his future plans.
From his observations, he also confirmed something—Hiruko had already prepared to leave Konoha the moment he acted against Kakashi. Or rather, his escape plan had long been in place.
Perhaps Hiruko escaping from the Sannin hadn't been due to their mercy after all?
But regardless of the truth, none of that mattered to Kurogane Ren anymore.
He had what he came for.
After confirming everything, he withdrew his crows and let them roam freely within Konoha, while he devoted all his attention to the Demon Assimilation Technique.
And so, several days passed.
Looking at the final experimental record—and the blank space that followed—Kurogane Ren slowly closed his eyes before opening them again.
Within them were both excitement and regret.
The exciting part was that the Demon Assimilation Technique was now barely usable.
The regret was that it had a clear limit.
According to Hiruko in the original story, fusing five bloodline limits would grant immortality.
But Kurogane Ren didn't believe that—not even one percent.
As far as he knew, true immortality existed only in beings like Kaguya Otsutsuki, who could only be sealed, not killed.
And Hiruko thought he could achieve that with just five bloodline limits?
Ridiculous. Even a Kekkei Mora couldn't accomplish that.
Moreover, in the original story, Hiruko never actually succeeded in fusing five bloodline limits. It was nothing more than a theoretical concept.
Kurogane Ren knew what lay ahead—figures of godlike power. Even Obito Uchiha and Madara Uchiha, with Six Paths power, failed to achieve true immortality.
So how could the Demon Assimilation Technique possibly do it?
But none of that was a problem.
First, unlike Hiruko, he wouldn't waste fusion slots on ordinary bloodline limits. With his "Heavenly Eye," even relying solely on this technique, he would far surpass Hiruko.
Second, a faint smile appeared on his lips. He had long since planned what to do after obtaining the technique.
Standing up, he stretched, his bones cracking in protest after days of overwork.
He hadn't slept in days. Naturally, he wanted to rest—but his stomach was empty.
At the very least, he needed to eat before collapsing.
Finally, Kurogane Ren pushed open the door that hadn't moved for days.
Too exhausted to care about anything else, he gathered chakra at his feet and formed a quick hand seal.
"Body Flicker Technique!"
His figure vanished instantly.
Not long after, he returned home.
This time, he didn't bother with anything. He threw himself onto the bed and fell into a deep sleep.
As for washing up… that could wait until he was rested.
He was completely drained.