The emergence of a relatively successful test subject like Zabuza brought Shinji some satisfaction, but the research into "Shinjutsu" was still in its nascent stages.
Regarding Zabuza himself, Shinji viewed him primarily as research material rather than someone worth cultivating as a subordinate.
Firstly, Zabuza's rebellious and untamable nature made him difficult to control. Investing heavily in such an individual carried risks that far outweighed the potential rewards.
Secondly, the chakra of Otsutsuki Shibai carried the residual will of that specific Otsutsuki. While it wasn't quite at the level of a "Karma" seal, it undeniably influenced every test subject. To put it simply, the chakra of every subject transplanted with Shibai's cells—including Eida and Daemon—was stamped with a "security tag" belonging to Otsutsuki Shibai. Their chakra was no longer pure; consequently, aside from further transplantations of Shibai's power, they possessed almost no other means of increasing their personal strength.
In other words, without undergoing additional transplant surgeries, the strength ceiling for Eida, Daemon, and Zabuza was fixed. It was virtually impossible for them to grow stronger through traditional training.
Therefore, while these subjects might currently rival Karin, Hikari, or Shion in raw power, their long-term potential was far lower, making their developmental value minimal.
What Shinji truly needed wasn't the subjects themselves, but the data derived from creating successful cases. He wanted to deconstruct Otsutsuki Shibai's chakra and analyze the true secrets of Shinjutsu. Once those secrets were unraveled, Shinji's own strength could reach a new level.
This was vital for Shinji, who had already reached the pinnacle as a Kekkei Mora. At his current height, further progress was exceptionally difficult, leaving him with only a few options: mastering rare high-level dojutsu bloodlines or consuming "Chakra Fruits."
Another two weeks passed quickly.
As cell transplantation technology matured and auxiliary agents like fusion catalysts, inhibitors, and dissolvents were successfully developed, the survival rate of the surgeries improved drastically. Many subjects whose bodies could not handle Shibai's cells were still able to survive with the help of inhibitors and dissolvents.
The plummeting mortality rate led to a rapid surge in volunteers. More and more shinobi proactively joined the trials—even Jonin like Zabuza were no longer rare sights.
With the increase in high-quality test subjects, research breakthroughs began to snowball. Whereas only seven cases had succeeded out of the first two thousand trials (and only Zabuza's was a "true" success), the last two weeks saw only 1,200 trials but resulted in twenty-two preliminary successes!
Due to this influx of successful subjects, the Institute had to dedicate significant energy to screening them individually to test who among them had actually obtained a "Shinjutsu."
Testing these empowered individuals was no easy task. There weren't many experts in the Institute qualified to spar with them. Consequently, Haku and Yakumo had to personally step into the arena. Eventually, the Institute was forced to requisition existing subjects like Daemon and Zabuza to act as testers.
Test Ground No. 12.
Thud!
Accompanied by a muffled impact, a figure was sent flying. Zabuza's sinister laughter echoed through the testing ground: "Heh, is this all you've got? If so, get lost! I'm worried I'll accidentally kill you with one punch!"
Undoubtedly, Zabuza thoroughly enjoyed his new role as a tester. Ravaging one subject after another who had survived the same surgery gave him a warped sense of pleasure.
At the edge of the field, researchers operated various instruments, collecting data from the combat. All information was funneled to a data center where specialized analysts scrutinized the chakra signatures. Through this precious data, they were bit by bit deconstructing the mystery of Shinjutsu.
Control Center.
Through a series of monitors, Shinji and Amado observed the situation across the various testing grounds. Looking at these subjects—the weakest of whom could rival a Kage-level shinobi—a shadow of worry flitted through Amado's eyes.
Many of these subjects were criminals captured earlier. Even excluding the criminals, the volunteers were not necessarily reliable. As the success rate continued to rise, the group of individuals wielding the power of Otsutsuki Shibai would only grow larger. At this rate, they would soon become a massive force that even Shinji might find troublesome to manage.
After a moment of silence, Amado asked, "Leader, should we temporarily halt the cell transplantations? We have enough experimental material for now."
"No," Shinji shook his head.
He was more aware of the hidden dangers than Amado was, but under the looming threat of the Hegemons, he could not stop—at least not now.
Amado countered, "These people are highly uncontrollable. If a riot occurs, our personnel might not be able to suppress it immediately."
Shinji's voice was resolute: "I will add more manpower. The trials must continue."
To handle these subjects, aside from conventional sealing and restraint, Shinji had another ace up his sleeve: he could have Hikari use Yachihoko to mark every subject, allowing him to secretly collect their chakra.
If the subjects dared to revolt, Hikari could use Yachihoko to extract their chakra in bulk, weakening them instantly to assist the guards.
Of course, every coin has two sides. The chakra attributes of these subjects were, without exception, being assimilated by Otsutsuki Shibai's chakra. When gathered together, their chakra didn't suffer from attribute-based loss, making them the highest quality "fuel" for Yachihoko.
However, this "high-quality" source was also a threat. The chakra didn't just assimilate the subjects; it would also attempt to assimilate Hikari if she absorbed it in large quantities. Shinji was currently nursing a headache over how to purify this specific type of chakra.