Hidden Leaf Hospital.
Covering his eyes, Sasuke climbed off the examination table and asked Tsunade and the others at the equipment, "How's my condition?"
Tsunade glanced at the data on the instruments and shook her head.
Kakashi, standing nearby, grew anxious. "Is it bad?"
Tsunade replied, "Sasuke, if I'm not mistaken, the vision in your Sharingan has deteriorated significantly, hasn't it?"
Sasuke's face darkened.
Tsunade continued, "From the data, the dojutsu power of your Mangekyo Sharingan hasn't changed much compared to half a month ago."
Sakura gasped, shocked. "How is that possible? Sasuke hasn't used his Mangekyo Sharingan at all during this time. Why hasn't his dojutsu power recovered?"
Tsunade said casually, "Who told you the Mangekyo Sharingan's dojutsu power can recover?"
"What!?"
Not only Sakura but even Naruto exclaimed in shock.
Sasuke and Kakashi's expressions grew grim. Though they either knew or suspected this, hearing the definitive judgment from Tsunade, the most authoritative medical shinobi, made their hearts sink.
Tsunade explained, "I've studied the Second Hokage's research notes. The Mangekyo Sharingan isn't a stable state. In recorded history, those who awakened it had short lifespans. While wars and vendettas played a part, the root cause is the Mangekyo Sharingan's instability, which places an immense burden on its user."
Yakumo nodded deeply, relating to the explanation. Before successfully transplanting the First Hokage's cells, she had endured the strain of her Koryugan through sheer willpower. Without the transplant improving her constitution, she felt she would've been dragged to her death by the Koryugan within a year or two.
Kakashi asked, "Is there a way to fix it?"
Tsunade shook her head. "The Mangekyo Sharingan is essentially a consumable. Within the Uchiha Clan, it's called the 'Cursed Eye' because it's said that once awakened, it inevitably leads its user to a dark abyss."
"The Cursed Eye, huh?" Sasuke gave a bitter smile.
Naruto urged, "Granny Tsunade, you must have a solution, right?"
Sakura added, "Speaking of dojutsu power depletion, Lady Tsunade, the Akatsuki's 'A' and 'B' became famous before Sasuke. Wouldn't their Sharingan's dojutsu power be nearly exhausted by now?"
Tsunade glanced at Sakura, surprised. She hadn't expected Sakura, who was unremarkable in the Academy, to make such a sharp observation. "Yes, logically, 'A' and 'B' from the Akatsuki should have depleted their Mangekyo Sharingan's dojutsu power far more than Sasuke. Their power should've been exhausted long ago, but reality suggests otherwise!"
To counter the Akatsuki's 'A' and 'B,' the Five Great Shinobi Villages had conducted in-depth assessments of the Sharingan. In terms of consumption, 'A' and 'B' activating their complete Susanoo would undoubtedly surpass Sasuke's usage. Yet, during the battle in the Land of Grass, neither showed signs of dojutsu power depletion like Sasuke's.
"Could the Akatsuki have found a way to address dojutsu power loss?" Kakashi asked Tsunade, though his eyes flicked toward Sasuke.
Sasuke remained silent, deep in thought. When Shinji, as 'A,' had contacted him, he revealed the secret of the Eternal Mangekyo Sharingan. Sasuke knew there was an ultimate form of the Sharingan above the Mangekyo. However, achieving it came at a steep cost: fusing with another pair of Mangekyo Sharingan from a close blood relative.
Learning this, Sasuke became convinced that Itachi spared him during the Uchiha massacre to one day take his Mangekyo Sharingan to achieve the legendary Eternal Mangekyo Sharingan.
Yakumo, meanwhile, had another theory. During the great battle in the Demon Slayer world, 'B' had used Wood Release just like her. Unaware of the Eternal Mangekyo Sharingan, she suspected 'B' restored dojutsu power by transplanting the First Hokage's cells. As a beneficiary of the transplant herself, Yakumo knew better than anyone in the room how transformative its effects were.
Softly, Yakumo asked, "Lady Tsunade, could transplanting the First Hokage's cells solve this issue for Sasuke?"
Tsunade frowned, considering the idea.
Everyone else, including Sasuke, was taken aback by Yakumo's suggestion.
After a moment, Tsunade said, "The First Hokage's cells contain Yang Release chakra, representing ultimate vitality. In theory, if Sasuke underwent the transplant, any physical change is possible, including restoring dojutsu power."
Prompted by Yakumo, Sasuke recalled 'B' using Wood Release in the Demon Slayer world. His eyes flickered as he thought, "Could 'B' have restored dojutsu power through the First's cells instead of fusing an Eternal Mangekyo Sharingan? Yes, awakening even one pair of Mangekyo Sharingan is incredibly difficult. How could the organization have two pairs for an Eternal Mangekyo?"
The more he thought, the more he believed 'B' used the First's cells to address dojutsu power recovery.
Gathering two pairs of blood-related Mangekyo Sharingan was simply too hard. He could barely accept 'A' having an Eternal Mangekyo Sharingan, but 'B' having one too?
That was harder to swallow, especially considering the Eternal Mangekyo was the ultimate form of the Sharingan.
...
Outside the examination room.
Shinji smiled and turned to leave.
He had overheard the conversation from outside but hadn't expected it to veer toward transplanting the First's cells.
Still, he wasn't worried. Currently, only Yakumo and Yamato were known to have successfully received the First's cell transplants in the village, and Yamato's case was only partial. Despite advancements in transplant technology, the procedure remained too dangerous for widespread use.
Even if Sasuke strongly requested it, the village wouldn't agree to perform the transplant on him in the short term. After all, Sasuke was the only Mangekyo Uchiha in the village. Losing him to a failed surgery would be a massive blow.
"Within a month, Sasuke should be fine. As long as he stays in the village, it shouldn't interfere with my attempt to awaken the Rinnegan," Shinji thought, reassured.
As for Sasuke's dojutsu power recovery, Shinji actually had a safer method, but at this critical juncture, there was no need to complicate things unnecessarily.