One bright, sunny morning, Habara arrived at the entrance to an archive located two floors beneath Konoha Hospital.
As always, it was dim inside; no matter how brightly the sun shone outside, not a single extra ray could penetrate down here. It couldn't be helped—Konoha ninja simply had a habit of burying everything underground, whether it was good, bad, important, or dangerous.
A ninja stood guard at the archive entrance, signaling the relative importance of its contents.
"Please present your identification or authorization," the ninja stated formally, adopting an official tone.
Habara hadn't brought standard ID, but he possessed something that sufficiently proved his identity. He pulled an object from his ninja pouch and displayed it. The guard immediately nodded and pushed a sign-in ledger forward. What Habara had shown was his "Senju of the Forest" medal, earned during the war—a decoration rarer and often more effective than any ID card.
This wasn't Habara's first visit. Since his human experiments had repeatedly failed, he often came here to sift through records, hoping to resolve his doubts and discover new research avenues and methods.
The archive's security classification wasn't excessively high, and Habara was a familiar face. Thus, the guard merely performed the routine check and confirmed Habara's access rights.
Habara signed his name in the ledger and recorded the date and time: December 5th, Year 51.
He then entered the archive, beginning his search among the rows of old bookshelves and yellowed papers for potentially useful knowledge.
He could comprehend most of the material if he didn't delve too deeply. The few parts that were excessively complex or obscure were unrelated to his research anyway—it wasn't like he was here to study medicine.
After searching for about an hour, he stumbled upon a completely handwritten thesis. "Neurotoxin Clearance in Ultra-High Temperature Environments; Restoration, Regeneration, and Cultivation of Cells Damaged by Toxin Effects" – that was the title inscribed on the cover. When Habara turned to the next page, which was nearly blank save for the author's name, he recognized the flamboyant, almost messy signature immediately: Tsunade.
One of the Sannin, a pivotal figure in Konoha's medical development history and the establishment of the four-person squad system, currently wandering the world, gambling and generally avoiding responsibility after leaving Konoha... In short, considering the author's identity, this thesis likely held significant weight.
Habara read through it, taking notes on key points. Soon, a new line of thought emerged.
His experiments had hit a wall, stalling progress. Now, he had potential solutions from two angles: further diluting the vaccine's concentration, and—inspired by Tsunade's work on high temperature effects—using low temperatures to suppress the vaccine's activity, thereby extending the subject's adaptation period.
To put it more simply, it was like turning potent chemical fertilizer into a slow-release version. The nutrients had to be released gradually during the plant's growth cycle to avoid burning the roots with excessive initial potency.
Referencing Tsunade's paper and the medical cases she summarized, Habara revised the experiment duration to 48 hours.
The first twenty-four hours of this revised experiment would involve slow contact and fusion between the vaccine and the test subject within a low-temperature environment. The subsequent twenty-four hours would involve gradually increasing the temperature, allowing the subject to progressively adapt to the vaccine's gradually increasing activity.
Stretching an adaptation process that previously triggered a stress response measured in seconds into one measured in days would undoubtedly increase the experiment's success rate significantly.
The next day, Habara explained the new method for tormenting Tenzo.
"I just hope this time it works," Tenzo said, not adding much else, just sincerely voicing that wish.
"Relax," Habara replied. "This time, I have a strong premonition… a good one, of course."
He continued, "Simply put, we'll use low temperatures to control the 'vaccine's' activity. As you know, metabolic processes slow down in low temperatures, and molecular activity in organic matter also decreases. So, 'cold' is an excellent solution. There are two specific approaches: either make the vaccine itself low-temperature, or ensure the recipient's body temperature is lowered during and after injection."
"The logic is easy enough to follow," Tenzo conceded. "But there's one issue I wonder if you've considered… If a person gets too cold, they die. Isn't there a saying, 'cold as a corpse'?"
"Don't worry," Habara countered smoothly. "Fortunately for us, Konoha happens to possess a mature cryogenic life support system. The technology is impressively advanced; it's almost hard to believe."
On the third day, a cylindrical tank, along with a large pile of equipment most people wouldn't recognize, was transported deep into that forest clearing particularly suitable for, as Habara had previously joked, dumping bodies.
The participants were still the same three: Habara, Tenzo, and Daigo, gathered in the same remote cabin.
The various devices served several main functions: cooling, life support, and monitoring.
Habara and Daigo worked together, connecting various tubes and lines to the upright cylindrical tank, which was already filled with some kind of pale solution.
Tenzo still had the protective seals applied from the previous attempt. Once all preparations were complete, he was placed directly into the tank. After the lid was sealed, he looked rather like he was trapped inside a giant can.
Tenzo took the oxygen mask floating in the liquid and secured it over his face. He then gave Habara a thumbs-up, indicating he was ready.
Habara nodded, then pressed a button beside him.
The temperature inside the tank plummeted rapidly. Tenzo felt the warmth drain from his body. Within two or three minutes, his eyelids grew heavy. Passing a certain threshold, he drifted into a quiet sleep… the legendary sleep of an infant.
Habara's eyes were glued to a temperature gauge. He watched its needle dip below 0 degrees Celsius, continuing downward until it reached the lowest mark on the scale, where it finally stopped.
"Temperature control nominal, lowered to target value," Daigo reported crisply.
"Life signs monitor nominal, subject's vitals stable."
"Subject entering deep sleep state."
Daigo's status reports sounded periodically.
A thin mechanical arm suspended above the tank slowly descended. At its end was a syringe. A long wait ensued as they monitored Tenzo's deep sleep state. Finally, Daigo announced, "Optimal window reached. Injection conditions met."
Habara took a deep breath. "Proceed with injection."
As Habara activated the mechanism, the needle pierced Tenzo's right shoulder.
"Vaccine activity low, remains controllable…" Daigo continued her reports.
"Corrosive activity minimal, peak values within acceptable range."
"No stress response detected."
Five minutes, ten minutes, half an hour passed…
After the better part of half a day had passed, Habara finally let out a sigh of relief. "See? I told you Wood Release and natural energy were compatible. Their affinities can't conflict. From this, we can conclude that derivatives of the First's cells and the Curse Mark can be fused. We just needed to find the right method."
One day passed. The first phase concluded without incident. After the second phase began—involving the gradual increase of temperature—Tenzo's sleeping body struggled and convulsed several times. Fortunately, the life monitoring systems didn't sound any alarms, and his vital signs, while fluctuating, didn't spike or drop too drastically. By the final three hours of the experiment, Tenzo's condition stabilized once more.
"At this point… can we say it's stable?" Habara asked, unable to fully suppress the excitement in his voice.
Daigo had been ready to intervene at any moment, poised for rescue, but this time, it seemed her emergency measures wouldn't be needed.
Habara walked to the side of the tank, peering through the viewport. He could see dark red markings spreading out from the injection site on Tenzo's shoulder. Lines radiated from the central point, extending in peculiar curves before meeting… It wasn't a standard geometric pattern, but it possessed a natural rhythm, resembling a lotus flower blooming beneath the skin.
At that moment, observing the pattern form, he felt like success or failure hinged on this outcome.
"Don't celebrate too soon," Daigo cautioned calmly. "Only a quarter of the observation period has passed."
Habara nodded, reigning in his elation. Initial success didn't guarantee the final result. He refocused his attention on the ongoing monitoring.
......
Eventually, Tenzo groggily regained consciousness. A lingering ache in his shoulder made him instinctively turn his hazy eyes downward… He saw the round, intricate red mark there. For some reason, in his dazed state, it looked exactly like the "Quarantine Approved" stamps he'd seen on slabs of pork in the market.
He didn't know why, but the words Quarantine Approved floated inexplicably into his mind.