After leaving Karin's apartment, Uchiha Shinji began preparing for the upcoming eye transplant surgery.
He first infiltrated the Forest of Death, returning to a hidden cave where he adjusted the Mangekyō Sharingan he was currently using. He removed the right eye of his grandmother, Uchiha Naori, which held the dojutsu Jikibi.
After placing his grandmother's Mangekyō Sharingan into a nutrient tank, Shinji pondered.
Currently, he was wielding Uchiha Fugaku's pair of Mangekyō Sharingan, which granted him the abilities of Amaterasu and Izanagi-no-Mikoto.
This meant that until Karin fully restored his grandmother's Mangekyō Sharingan, he could no longer use Jikibi to communicate with others.
However, this recovery period wouldn't last long.
Given Karin's powerful sage-like body, once she entered the stabilization phase, restoring a Mangekyō Sharingan should take no longer than a week.
"Once Karin restores my grandmother's Mangekyō Sharingan, I'll be able to directly fuse the eye powers using Susanoo Tomoshibi."
The thought made his heart race with excitement.
Still, Shinji knew that the closer he got to achieving his goal, the more he needed to remain calm.
Next, he reflected on the process of fusing the eye powers.
Without the Susanoo Tomoshibi dojutsu, even if he had a pair of blood-related Mangekyō Sharingan, he would need to undergo surgery to fuse them.
But surgical transplants often required a long fusion period.
In the original timeline, Sasuke had taken considerable time to recover after transplanting Itachi's Mangekyō Sharingan while resting in a secret base arranged by Tobi.
The exact duration was unclear, but Shinji estimated it to be anywhere from a few weeks to a month.
During the fusion period, the eyes couldn't be used, meaning Shinji, living in Hidden Leaf Village, couldn't afford to fuse his Eternal Mangekyō Sharingan through surgery.
Even using Susanoo Tomoshibi to fuse the eyes might cause unforeseen reactions in his body.
At this point, Shinji took out a pair of fully damaged Mangekyō Sharingan.
Staring at the yellowed, completely power-deprived eyes floating in the nutrient solution, he sank into thought.
When he helped Karin reactivate the previously blind Mangekyō Sharingan, he had a strange sensation—almost as if the Mangekyō was being reborn, not just restored.
For a brief moment!
He even felt a close connection between the Mangekyō Sharingan and Karin, as if the eye was becoming part of her.
"Could it be that restoring the eyes through Karin creates some sort of bloodline bond between the Mangekyō and her?"
This thought stirred within Shinji's mind.
However, because the left eye of that pair had retained its power, the right eye's anomaly was quickly corrected by the resonance between the two.
The close bond between the right eye and Karin dissipated, and the eyes stabilized as a pair.
But what if both eyes were fully damaged and had lost their sight? If Karin could restore such a pair, would that same sense of a bloodline bond persist?
And if that were the case...
Whom would the restored Mangekyō Sharingan belong to?
Would they still belong to the original owner?
Or would they now belong to Karin?
This was a crucial question. If the restored Mangekyō Sharingan were considered Karin's, she might possess the potential to wield an Eternal Mangekyō Sharingan.
Here, "possess" didn't mean simply transplanting an Eternal Mangekyō into her.
It meant Karin could fuse the eye powers herself, creating a pair of Eternal Mangekyō Sharingan that were truly hers, bound by her bloodline.
Only one's own eyes could continue evolving. If Karin could achieve this, combined with her powerful sage-like body inherited from both the Uzumaki and Senju clans, she might have the potential to awaken the Rinnegan.
Although this was merely a theoretical possibility that couldn't yet be proven...
...
The next morning.
As usual, Shinji arrived at the medical team's lab.
He began by using the instruments to analyze the cellular data from the sample he had taken from Kimimaro's cells, carefully recording the results.
Then, along with Kusadō Kaoru, he was sent by the medical team to the Hidden Leaf Hospital to treat patients.
If not for the fact that Shinji was still a student at the academy, the medical team would have almost treated him as a fully certified medical shinobi.
It wasn't until dusk that Shinji, feeling a bit fatigued, finally walked out of the hospital.
Kusadō Kaoru, who was also leaving, stretched and complained, "Ah, to be young. Unlike me, who can't keep up after a full day of work!"
You're only in your twenties! Shinji thought to himself, smiling as he bid farewell. "See you tomorrow, teacher!"
While working with patients directly was exhausting, it gave Shinji real-world experience in applying medical ninjutsu to different types of injuries, deepening his understanding of the art.
Thus, he didn't mind being dragged into such work by the medical team.
On his way home, he saw Lee, drenched in sweat, running laps around the village.
He saw Neji, diligently practicing the Gentle Fist under Tenten's support, using various ninja tools.
He even spotted Naruto mischievously painting graffiti on the Hokage Rock while Iruka chased him through the village.
"So the holiday break has officially begun."
Shinji smiled, shaking his head as he grabbed a bite to eat at a small roadside restaurant before heading back to his apartment.
Time passed, and Shinji looked up at the clock on the wall. Seeing that midnight was approaching, he closed the medical ninjutsu book in his hands.
He donned his Akatsuki robe with the red clouds, put on his mask, and disappeared from the apartment in a flash.
Soon, he was at Karin's apartment, where she quietly let him inside.
Since this wasn't their first time, Karin was much more relaxed now.
She watched curiously as Shinji laid out the surgical instruments from his kit and sterilized each tool with practiced precision.
Once everything was ready, Shinji turned to Karin. "The pair of Mangekyō Sharingan I'm transplanting into you tonight is similar to the ones you already have. One of them is blind."
"I understand."
Karin nodded softly.
The moment she learned that Shinji was giving her another pair of Mangekyō Sharingan, she knew he was relying on her to restore them once again.
As he took out Uchiha Naori's Mangekyō Sharingan, Shinji reminded her, "These eyes are extremely important, so be careful."
"Yes!" Karin's expression grew serious.
Without further words, Shinji had Karin lie down and immediately began the transplant surgery.
As the procedure progressed, Shinji once again noticed the difference between Karin and ordinary patients.
In any other person, he would have to be extremely cautious about the incisions. But in Karin's case, the moment he made a cut, her body would instantly stop the bleeding and begin healing.
If he worked too slowly, the wound would heal before he could even finish the surgery...