"Yawn..."
In the classroom, Uchiha Shinji let out a long yawn.
Haku turned around to look at him, "Shinji, did you not sleep well last night?"
"A little," Shinji nodded.
He had been busy until late at night, carefully using Susanoo Tomoshibi to inspect all the Sharingan he had obtained, ensuring he didn't miss anything.
The final haul included two pairs of half-damaged Mangekyō, one completely ruined Mangekyō, and ten pairs of usable but varying-condition three-tomoe Sharingan.
With such a bounty, it was enough to make him smile in his sleep. No wonder he didn't get much rest.
"Is it because of the attack?" Haku hesitated for a moment before continuing, "I heard you were attacked again last night?"
"Yeah," Shinji nodded, his reaction calm.
Haku then asked, "Have they figured out who the attacker was? Why did they target you?"
"They're probably still investigating," Shinji replied, gazing out the window.
He couldn't predict what Danzo would do next, but as long as his previous actions remained hidden, Danzo couldn't openly move against him.
As for assassinations like last night...
Honestly, Shinji wasn't afraid. In fact, he was somewhat looking forward to it.
Such high-stakes combat was far more beneficial than regular sparring. After yesterday's battle, even Neji and Sasuke showed noticeable improvement.
Seeing Shinji deep in thought, Haku didn't press further and simply said, "Shinji, if you need help, you can come to me."
Shinji smiled, "Thanks, I will."
He appreciated Haku's offer, but his concern wasn't really about Danzo. What worried him more was how to maintain the Sharingan he had collected.
His grandmother Uchiha Naori's Mangekyō was relatively safe for now, as it could stay in the nutrient tank without immediate risk of decay.
But the other half-damaged Mangekyō didn't have much time left.
If he didn't find a host to transplant it into soon, allowing it to be nourished by chakra, it would likely deteriorate completely in a matter of months.
However, Shinji couldn't just swap out his own Mangekyō to nourish it with his body's chakra. Being left with one eye would severely weaken his combat ability, leaving him vulnerable in case of an emergency.
As his thoughts drifted, his gaze roamed around the classroom aimlessly.
Suddenly, his eyes fell on Karin, who sat in the front row with her vibrant red hair.
"Karin!"
If he had to pick someone with a body most similar to the First Hokage's in the current ninja world, it would undoubtedly be Karin.
As a member of the Uzumaki Clan, possessing the same Sage Body as the Senju Clan, Karin's physique was far superior to that of ordinary people.
Add to that her unique, healing-boosting, Yang-nature chakra, and she was the ideal candidate for nourishing a Mangekyō.
This wasn't just Shinji's imagination.
After all, Uchiha Madara, before his death, had also entrusted his Rinnegan to Nagato, another member of the Uzumaki Clan.
It was clear that only those like the Uzumaki, with their Sage Body, could endure and nurture eyes brimming with powerful dojutsu.
Shinji's mind started to race.
In the future, if he obtained White Zetsu cells, Karin could be the perfect candidate for testing them.
Her strong life force, inherited from the Uzumaki Clan, might face some risk in handling the First Hokage's dominant cells. But if it was White Zetsu cells, which even half-dead Obito could withstand, there should be no problem.
White Zetsu cells, cultivated from the God Tree and the First Hokage's cells by Madara, contained the Senju Clan's powerful Yang-nature chakra.
If Karin successfully received them, she would possess both the Uzumaki and Senju Sage Body, and her Yang chakra could rise to an entirely new level.
At that point, she could become an even better chakra battery than White Zetsu!
Nurtured by such powerful Yang-nature chakra over time, there might even be hope for restoring the sight of the blind Mangekyō.
"If I were to transplant an Eternal Mangekyō Sharingan into Karin, could it possibly evolve into the Rinnegan?"
Shinji's thoughts began to spiral out of control.
He was very familiar with the process of Uchiha Madara's Rinnegan awakening:
It involved Madara using his half-damaged Eternal Mangekyō Sharingan, then implanting the First Hokage's cells to gain the powerful Yang chakra inherent within them, thus achieving a Yin-Yang fusion and unlocking the Shinra Banshō (All-Creation Power)!
Not only did this fully restore his damaged Eternal Mangekyō, but it also evolved into the Rinnegan.
In simpler terms:
It was the powerful Yin chakra from the Eternal Mangekyō Sharingan combined with the potent Yang chakra from the First Hokage's cells, resulting in the fusion of Yin and Yang.
By reversing this process:
Using a strong Sage Body as the host, transplanting an Eternal Mangekyō Sharingan, changing it from Yin + Yang to Yang + Yin, it could theoretically achieve the same Yin-Yang fusion, unlocking the Shinra Banshō.
As for the whole Indra and Asura reincarnation thing, Shinji scoffed at it.
With his understanding of the shinobi world, he knew that the two sons of the Sage of Six Paths didn't possess any irreplaceable special traits.
Everyone was a descendant of Kaguya Otsutsuki.
Trace the bloodline far enough, and it all led back to that chakra originator!
The only difference was that Indra and Asura's chakra was of a higher grade, making their reincarnations more likely to achieve a Yin-Yang fusion.
This explained why, for generations, only the reincarnations of Indra and Asura managed to unlock the Rinnegan, until Uchiha Madara finally succeeded.
But if someone fully understood the principles behind Rinnegan evolution, others would have a chance as well.
After all, it all came down to chakra manipulation!
"Shinji, why are you staring at Karin so intently?"
Haku's voice snapped Shinji out of his wandering thoughts.
Shinji quickly withdrew his gaze, offering a casual excuse to Haku while silently chastising himself:
"Sigh, how did I start thinking of Karin as a test subject?"
Even if such things were to be done, Shinji thought he should at least get Karin's consent first.
At the very least, it should be mutually beneficial.
Not long after, the bell rang, signaling the end of class.
Shinji quickly left the classroom and caught up with Iruka-sensei, who had just finished teaching.
Inside the teacher's office, Iruka looked at Shinji and said, "I suppose you came to ask about last night's attack? Don't worry, even though we haven't identified the attacker yet, the academy is absolutely safe!"
Shinji shook his head, "That's not why I'm here. I wanted to ask for permission to learn medical ninjutsu!"
"What!?"
Iruka was baffled by Shinji's unexpected request.