After Orochimaru left, Aoba stepped out of the room. Through the crack in the neighboring door, little Karin was peeking at him.
"It's alright, no need to worry. The snake is gone.""Oh, that's great. I'm terrified of snakes. They're so disgusting."
"Really? I feel the same way, actually."
That was the truth. Orochimaru's snake-based ninjutsu was genuinely unsettling on a physiological level.
"Alright, Karin, come here. Let me check your condition."
"Okay."
Aoba wasn't a professional medical ninja. However, during his time under Orochimaru, he had learned some medical knowledge. He had actually considered specializing in medical ninjutsu—it seemed safer.
But there were two issues. First, the ceiling for growth was too low. Second, having been reborn into this world, how could he not pursue greater power?
Karin was still young. Though she had been bitten many times, her foundation was strong. After this period of proper nourishment and care, her body had recovered quickly.
Even the bite marks on her body were gradually fading.
"Your recovery is going very well. At this rate, you'll be completely fine in another week. Then, you can start attending school."
"School? I have to go to school? Aoba-nii, I don't want to..." Karin instinctively began to whine, but Aoba firmly shut her down.
"School is non-negotiable. I often have missions and won't have time to teach you. School will help you learn and solidify basic ninja knowledge. Most importantly, it'll let you meet peers.
Don't worry—Konoha is nothing like Kusagakure. The students here are decent. You'll make new friends. It'll be good for your growth."
Aoba left out one reason: Karin was from the Uzumaki clan and had innate Chakra reactions. If she didn't attend school, it would raise suspicions.
After all, Konoha wasn't entirely safe either. With Danzo, the "Shadow of the Hokage," lurking around, Aoba had to stay vigilant.
Sending Karin openly to school would dispel prying eyes. Yumi knew this reasoning, but Karin was too young for such explanations.
In contrast to Karin, Yumi's condition wasn't as optimistic.
Though her health had stabilized after this period of recovery, that was all. It hadn't worsened, but it hadn't improved either.
Yumi wasn't actually old—just a few years older than Aoba, around 24 or 25.
Given the Uzumaki clan's constitution, she should have recovered quickly. The fact that she hadn't meant her life force had been severely depleted.
The Kusagakure ninjas had treated her inhumanely, biting her deliberately and harshly, leaving her body on the brink of collapse.
"Sir, you can tell me directly. How long do I have left?"
"I told you, just call me Aoba. At this rate, you have about two to three years."
"That's enough. At least I can spend these last years with Karin."
"Don't be so pessimistic. I told you—I have a way to save you. It just takes time and carries some risk."
"I trust you. When the time comes, let me know. No matter how high the risk, I'm willing to try."
"I will."
Yumi's situation was complicated. Her life force had been excessively drained—this wasn't an ordinary injury.So, biting Karin was completely out of the question.
During this time, Aoba had carefully studied the unique physiques of the two girls. Initially, he thought their blood was responsible for healing injuries.
But later, he realized that wasn't the case—at least not entirely. While their blood did contain immense vitality, simply ingesting it wouldn't produce such rapid recovery.
Blood needed to be absorbed by the body before the vitality within could be utilized.
The actual mechanism was that the moment their bodies were bitten, the vitality within would flow out with the blood and directly enter the biter's system.
This was what enabled such swift healing.
However, this recovery only mended external injuries—it couldn't replenish the target's life essence. Therefore, having Yumi bite Karin wasn't a viable solution.
This was an extremely complex subject. Even as a professional, Aoba couldn't fully unravel its mysteries in a short time.
He deduced that biting was likely only a superficial method of utilizing and absorbing vitality.
To replenish Yumi's life force, a deeper-level supplement was needed. But how to achieve that remained unclear for now.
Aoba had already decided—if this path led nowhere, he would resort to his own method: transplanting Hashirama Cells. If successful, it would undoubtedly restore—or even enhance—her vitality.
A week later, Karin was reluctantly sent to school by Aoba.
After completing several missions in succession, Aoba finally secured an extended leave. He then began his research in the basement of his home.
Orochimaru was highly efficient. Within three days, materials on sealing techniques and various experimental equipment were delivered.
Honestly, Aoba envied Orochimaru's seemingly endless supply of funds and instruments.
Purchasing these items himself would have cost tens of millions, if not hundreds of millions, of ryō. Yet Orochimaru simply handed them over without hesitation.
Afterward, Aoba set up a basement beneath his house, converted it into a lab, and began advancing his research.
The Hashirama Cells had arrived, but another condition remained unmet, so he held off on using them for now.
His current focus was still Karin.
Her physique was undeniably practical. But Aoba wasn't a pervert like the Grass ninja—he wouldn't drag a little girl around as a walking blood bag.
Yet he couldn't ignore the potential benefits. So, his idea was to periodically extract a portion of Karin's vitality—without harming her health—and store it for emergencies.
The girl's vitality was extraordinarily robust. While supplying an entire village like Grass would be unsustainable, drawing a single vial of blood per week would hardly affect her.
But this raised an issue: as previously mentioned, Karin's vitality wasn't solely in her blood—it spilled out along with it.
And it was this spilled vitality that enabled rapid healing. Aoba's goal was to find a way to seal and preserve this excess vitality, turning it into a restorative potion.To achieve this, medical techniques and the cooperation of sealing techniques were necessary. This was also the reason he had requested sealing technique materials from Orochimaru.
For most of his research to delve deeper, sealing techniques were indispensable.
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