After a few days of rest, Sasuke had fully recovered.
In the hospital room, he stretched his body and asked Kakashi, who was engrossed in his novel, "Kakashi, when can I leave the hospital?"
Kakashi didn't look up. "Your body's recovered, sure, but I suggest staying a few more days. The Mangekyo Sharingan puts a heavy strain on your body, and at your age, it's likely tough to handle."
"I'm fine!"
Sasuke brimmed with confidence.
Kakashi glanced at him. "If you're itching to leave just to challenge Yakumo again, I won't allow it."
Sasuke frowned. "Why not?"
Knowing what Sasuke cared about most, Kakashi coaxed, "Don't you want revenge? What's the point of challenging Yakumo again? It'll only leak more of your abilities!"
Sasuke hesitated, conflicted.
He knew overusing the Mangekyo Sharingan could expose his capabilities, but his crushing defeat to Yakumo gnawed at him. He couldn't accept that he, awakened to the Mangekyo Sharingan, had lost so badly to her.
The thought made him reluctant to face his peers at the shinobi academy.
Seeing Sasuke waver, Kakashi pressed, "Your last challenge was too hasty."
"Hm."
Sasuke nodded.
Over the past few days, he'd reflected and realized that challenging Yakumo right after awakening his Mangekyo Sharingan—and after having his chakra drained all night by the leader—was recklessly impulsive.
Kakashi lifted his headband, revealing his Sharingan. "When I first got this Sharingan transplanted, it took me a long time to barely adapt. The Mangekyo Sharingan's power far surpasses the tomoe Sharingan, so it's likely even harder to master."
Sasuke retorted stubbornly, "I've already adapted!"
Kakashi smiled. "When Yakumo first underwent her surgery, didn't Shinji defeat her too? The stronger the power, the more time it takes to tame."
At the mention of Shinji, Sasuke's expression grew uneasy.
Noticing, Kakashi asked, "By the way, have you talked to Shinji?"
Sasuke shook his head.
Kakashi advised, "Didn't you say you challenged him with the intent to kill? You should find a chance to talk things out."
If anyone in the Hidden Leaf, aside from Shinji and Sasuke, understood the Sharingan best, it was Kakashi, who had a transplanted one.
Though Sasuke had glossed over the details of that night's challenge, Kakashi knew from the fact that Shinji could push Sasuke to awaken the Mangekyo Sharingan that Shinji held an unparalleled place in Sasuke's heart.
People might deceive themselves, but the Sharingan never lies!
Meanwhile, Shinji, the subject of their conversation, was busy with his own affairs.
With Sasuke hospitalized after his defeat to Yakumo, Shinji naturally wouldn't risk continuing to drain Sasuke's chakra. As a result, Karin's progress toward the Rinnegan was delayed.
However, Shinji still had his "Tenseigan Plan," so he wasn't idle.
Over the past few days, he'd gradually felt the conveniences brought by Sasuke's Mangekyo Sharingan awakening.
Major privileges included full access to the village archives and the ability to freely request the medical corps' advanced labs. Minor perks ranged from doubled living stipends to excused absences from the shinobi academy without needing a teacher's approval.
These benefits showed the village's eagerness to win him over, and they undeniably aided his plans.
At that moment, he was in the medical corps' advanced laboratory, using cutting-edge equipment to analyze the properties of two chakra samples.
These samples were collected by the "bio-exoskeletons" implanted in Neji and Kimimaro.
Without such equipment, fusing these chakras would require Shinji to rely on Wazunagi for endless trial and error—a time-consuming and risky process.
With the equipment's analysis, he could determine the chakras' properties and adjust their fusion ratios, greatly increasing the chances of success!
After noting the data from the equipment, Shinji cleared its storage records, erased all traces of use, and returned the lab key.
Shizune, retrieving the key, immediately reported to Tsunade.
Tsunade asked, "What did he do in the lab?"
Shizune shook her head. "I checked the lab. There's no trace of anything. It's as if he didn't use it at all—just walked around."
"Borrowing the lab might just be a test of our attitude."
Tsunade didn't believe a ten-year-old academy student like Shinji actually needed such an advanced lab, assuming he'd requested access to probe the village's stance.
Back at his apartment, Shinji immediately began analyzing the data he'd collected.
The equipment's tests revealed that the two half "bio-exoskeletons" contained three types of chakra: Kimimaro's Kaguya clan Bone Pulse chakra, Neji's Byakugan chakra, and Tenseigan chakra Neji had harvested from the moon.
In terms of chakra strength, the Tenseigan chakra was indisputably the most potent.
Fortunately, Tenseigan chakra couldn't forcibly absorb Byakugan chakra, so Neji's Byakugan chakra, coexisting in the same "bio-exoskeleton" as the Tenseigan chakra, wasn't overtaken and retained its presence.
Comparing Kimimaro's Bone Pulse chakra to Neji's Byakugan chakra revealed a vast gap in strength, with Kimimaro's chakra far surpassing Neji's.
This puzzled Shinji, who briefly wondered if the equipment was faulty.
To verify, he compared his own chakra to Kimimaro's and found that Kimimaro's chakra strength was no less than his own.
"Thankfully, Neji can harvest the Giant Tenseigan's chakra on the moon. Otherwise, my 'Tenseigan Plan' would be impossible…"
Shinji quietly rejoiced.
Without the Tenseigan chakra to mediate, Neji's chakra could never fuse with Kimimaro's—their strengths were on entirely different levels.
Moreover, as Kimimaro's bloodline disease worsened, the strength of his Bone Pulse chakra was inexplicably increasing!
Fortunately, Neji had access to Tenseigan chakra.
Focusing his thoughts, Shinji began calculating the final chakra fusion for achieving the Tenseigan.
The fusion would involve three chakras stored in the "bio-exoskeletons" in Neji and Kimimaro—Kimimaro's Bone Pulse, Neji's Byakugan, and the Tenseigan chakra—plus the Ōtsutsuki chakra from the Byakugan pair Shinji had obtained from the moon's Ōtsutsuki branch family.
The Hyūga clan's Byakugan chakra, the Kaguya clan's Bone Pulse chakra, the Ōtsutsuki chakra from the moon's branch family, and the mediating Tenseigan chakra.
If the fusion succeeded, the Tenseigan would be within his grasp!