Within the underground laboratory situated at the edge of Konoha's Death Forest.
Tatsuya was engrossed in processing a clone body laid out on the experiment table. It was a failed specimen – a malformed clone. Ever since discovering the exceptional cell fusion properties of the unique 'one-eyed clone' cells, Tatsuya's lab hadn't produced a single failed, deformed specimen in over two years. This was the first such failure in that time.
The battle at Yakugakure, where Tatsuya's five clone bodies successfully repelled Akatsuki's attack, might have seemed like a resounding victory. In reality, however, the cost was immense. Jizo, Tatsuya's primary combatant possessing the Mangekyō Sharingan, was nearly rendered permanently unusable. Even after Tatsuya "revived" Jizo using the Earth Grudge Fear technique and a new clone body, his combat power would be significantly diminished. Uchiha Teru's Mangekyō Sharingan were nearing their absolute limit. Without them, Jizo's strength would be roughly equivalent to that of Kagutsuchi and Suijin. While their formidable taijutsu and vast chakra reserves would still rank them solidly at Kage-level, they would no longer possess the overwhelming power needed to dominate ordinary Kage-level opponents.
Perhaps their strength could be boosted by another ten or twenty percent if they could openly utilize the Akimichi clan's Butterfly Mode secret technique, but that was impossible under current circumstances.
The only viable path forward now was to use the special properties of the Blood Silkworm Silk to modify the three primary clone bodies (Jizo, Kagutsuchi, Suijin), enabling them to use Sage Art when necessary. This process, however, required time. Tatsuya planned to begin modifying the clones one by one after Jizo was "revived," which would take over a month.
The reason Tatsuya had deliberately stopped using the superior one-eyed clone cells for cultivation now was precisely because he wanted to attempt creating another malformed clone – hoping to replicate the unique mutation of the original one-eyed specimen.
Tatsuya still possessed the peculiar Mangekyō Sharingan from that original one-eyed clone. His research on it had continued uninterrupted for over two years. Through constant observation and study, Tatsuya discovered that this unique Mangekyō Sharingan, once transplanted into a living clone body, would continuously and automatically absorb negative natural energy from the surroundings. It was an extremely bizarre and dangerous ability. Tatsuya speculated that the transplantation of Blood Silkworm Silk onto its body had accelerated this absorption of negative energy, ultimately triggering the eye's evolution into a Mangekyō Sharingan in the first place. He even wondered if, left unchecked, the eye could eventually evolve into a Rinnegan.
Furthermore, that Sharingan possessed a space-time ability remarkably similar to Obito's Kamui. The allure of such an ability was incredibly strong for Tatsuya. However, he hadn't dared to attempt using it seriously. The eye, saturated with immense negative energy, was fundamentally uncontrollable and highly dangerous. The original one-eyed clone, under its influence, had even attacked Jizo unprovoked. Over the past two years, Tatsuya had tried numerous methods to purify the negative emotions contained within the eye, but none had succeeded. Reluctantly, he had been forced to seal the Mangekyō Sharingan away.
His current efforts to cultivate deformed clones were driven by the desire to gain new abilities through studying clone mutations extensively.
After spending the entire day in the lab and thoroughly disposing of the failed clone specimen, Tatsuya finally left. As he walked along the path towards the Ninja Academy, someone called out to him from behind.
Tatsuya turned, a flicker of surprise in his eyes as he recognized the person approaching. It was Itachi Uchiha.
"Tatsuya-san," Itachi greeted, coming closer and offering a respectful bow. Humble, good-natured, exceptionally talented – this was the impression Itachi gave most people. Regardless of whom he interacted with, this Uchiha prodigy was always impeccably polite.
"Itachi? What's up?" Tatsuya asked, slightly curious. This was the first time Itachi had sought him out proactively outside of mission duties.
"Tatsuya-san, could we speak somewhere private?" Itachi requested softly.
"Of course," Tatsuya nodded, agreeing immediately. In his current position, he no longer needed to be as excessively cautious as before.
Following Itachi to a secluded spot, Tatsuya asked, "Alright, what did you want to talk about?"
Itachi considered for a moment before speaking. "Tatsuya-san... the incident involving Elder Yashiro. Was that secretly carried out by you and Shisui-san?"
Tatsuya's eyebrows rose slightly in surprise. "Oh? Itachi, why would you ask such a thing? When the Uchiha Yashiro incident occurred, we were together in Kirigakure. And Shisui was stationed with the Military Police Force the entire time."
"Tatsuya-san, I'm actually aware," Itachi stated calmly, "that for the past two years or more, both Shisui-san and Misuke-san have maintained secret contact with you. While I don't know the specifics of the agreement you reached, I can clearly sense that they both trust you deeply. Around the time of Elder Yashiro's death, both Shisui-san's and Misuke-san's reactions were highly unusual. Misuke-san, especially, now openly associates with Kyoko-san without any reservations. Furthermore, the atmosphere within the clan has noticeably changed since that incident; it's not as volatile as before." Itachi laid out his analysis slowly, observing Tatsuya.
Hearing this, Tatsuya smiled. Itachi's perceptiveness exceeded his expectations. To deduce so much in such a short time after returning to the village...
"Heh, Itachi," Tatsuya chuckled, "that's all just your speculation. There isn't a shred of credible evidence to support it. Besides, isn't the shift in your clan's atmosphere exactly what you, Shisui, and the others have always hoped for? Why do you still appear so worried?"
Itachi's expression turned serious. "Someone has been secretly spying on the Uchiha clan."
"Oh? Who?" A glint appeared in Tatsuya's eyes. Has Itachi already encountered Obito?
Itachi shook his head. "I don't know who it is. I only found faint traces of his presence near the clan compound. This person is clearly very familiar with the Uchiha clan, but doesn't seem connected to the Hokage or Root. I suspect that Hiroaki-san awakening the Mangekyō Sharingan and defecting from the village might be related to this individual."
"Is that so?" Tatsuya raised his voice slightly, feigning surprise. "According to you, this person must be incredibly resourceful to move freely within the Uchiha clan compound like that." Yet, his eyes remained perfectly calm, betraying no actual surprise.
"Tatsuya-san," Itachi stated, looking directly at Tatsuya, "do you perhaps know who this person is?"
Tatsuya met Itachi's gaze. In the eyes of this thirteen-year-old boy, he saw unwavering conviction and composure. It was clear Itachi firmly believed his own judgment.
After a brief silence, Tatsuya replied, "I don't know his specific identity. However, I can confirm one thing: he is also a member of your Uchiha clan. Because his eyes... are also Mangekyō Sharingan. Furthermore, his space-time abilities are extremely strange. You should be very careful if you encounter him in the future."
"Mangekyō Sharingan!" Itachi murmured softly upon hearing this confirmation. "In that case... the true culprit behind the Nine-Tails attack back then... it must have been him!" He seemed somewhat unsurprised by this conclusion, as if it confirmed a long-held suspicion.