The Flying Thunder God Technique, developed by the Second Hokage, Senju Tobirama, is one of the most difficult ninjutsu to master, classified among the most mysterious space-time ninjutsu of all.
The records passed down through the Hidden Leaf Village detail a vast array of super high-level ninjutsu, so complex that only a few elite Jonin can hope to learn them. However, despite not being able to master these techniques, the Jonin must still be knowledgeable enough to identify them to prevent misuse in special circumstances. Thus, Maito Guy, as a Jonin, is aware of the Flying Thunder God Technique.
Moreover, the Fourth Hokage was Kakashi's esteemed mentor. His nickname, the Yellow Flash, arose from his numerous accomplishments in the ninja world, largely thanks to his proficiency with the Flying Thunder God Technique. So, when the Fourth observed Naruto closely for the second time, he realized just what Naruto had in his possession.
He was unaware of Naruto's true identity as the Fourth's son, or even if he had known, it wouldn't have affected his current thoughts.
After all, Naruto was still too young. Most of the sealing scrolls containing high-level ninjutsu in Konoha are only decipherable by Jonin. So even if Naruto came across such scrolls, he wouldn't be able to break the seals and learn the techniques contained within.
Instinctively, Guy suspected that someone wanted to manipulate the Nine-Tails residing within Naruto. They might have taught him the Flying Thunder God Technique from the sealing book.
Yet, Guy had to admit that no matter how he racked his brain, he couldn't understand how the person teaching Naruto this technique intended to utilize the Nine-Tails.
Moreover, it was difficult to discuss this with anyone. Although Guy, as a Jonin, often appeared carefree and a bit foolish, he was well aware of the underlying currents in the village.
Within Konoha, the upper echelons and the general populace were not unified. Neither the Root organization nor other prominent clans were necessarily aligned with the ideals of the Hokage and his ninja.
When it came to the Nine-Tails Jinchuriki, the Hokage had issued a clear and indisputable order to all ninjas above Chunin rank: minimize contact and treat him like a stranger.
Guy had been following this order himself. Initially, when he encountered Naruto, he was primarily concerned about the presence of members from the Hyuga clan near him. His aim was to gauge the movements of the Hyuga clan and understand why they were interacting with the Nine-Tails Jinchuriki.
But Naruto's actions made Guy realize something was amiss.
Logically, as the Jinchuriki of the Nine-Tails, Naruto shouldn't be in contact with any Konoha ninja who could teach him jutsu. Even if there were such ninjas, they would likely be unaware of the true situation, perhaps even lower-ranked genin or ordinary villagers.
If higher-ranked ninjas had contact with him, the Anbu would surely notice. So how could it be that Naruto was wandering around so freely?
As Guy suspected, if the ninjas within the village were unable to approach the Jinchuriki of the Nine-Tails, then who could teach such a small child to master such a high-level ninjutsu? The emergence of the Hyuga clan led him to a dangerously ominous conclusion—
The prominent clans in the village boasted experts at least on par with Jonin level, and with their extensive connections, if they colluded with the Anbu and engaged with the Nine-Tails Jinchuriki...
This reminded him of the Nine-Tails Incident from a few years ago, and the Uchiha clan's suspicion still loomed large. Guy felt he had stumbled upon a monumental secret; if mishandled, the village would undoubtedly plunge into an incredibly dire crisis!
That's why he had taken Naruto with him, intending to evade even the Anbu.
At this moment, Guy realized there was only one person in the entire village he could trust. Little did he know, his actions were, in some ways, quite perilous.
Hokage's Office.
"Guy has kidnapped Naruto Uzumaki?" The Third Hokage, swamped with paperwork and stressed about the disappearance of Shisui, was momentarily stunned when he heard the report from the Anbu. He instinctively asked, "Is it that Maito Guy?"
"Yes, he shouted something about Naruto having a powerful Body Flicker Technique before disappearing with him. The Anbu are currently in pursuit," the Anbu responded.
"A powerful Body Flicker Technique? Naruto?" The Third Hokage felt even more perplexed, but he quickly regained his composure. "I see, but I know Guy. Naruto shouldn't be in any da—"
"Sarutobi! I've heard someone has kidnapped the Nine-Tails Jinchuriki, and this is not something you can handle lightly!" An elderly man and woman, both high-ranking officials in Konoha, burst into the Hokage's office, exuding an air of righteous indignation. "Mobilize all Anbu to locate the Nine-Tails Jinchuriki, and bring back Maito Guy!"
"Enma, Koharu." The Third Hokage looked up at the two of them, advisors to the Hokage, who, like him, had once served in the Second Hokage's elite guard. "You're well-informed; the Anbu just notified me, and here you are already."
"Uh...," the elder advisor, Koharu, was somewhat speechless. She didn't want to admit that it was a member of Danzo's Root organization who had informed her, especially since the Third had previously declared that Danzo and Root should not contact the Nine-Tails Jinchuriki.
"These details don't matter. The key issue is the whereabouts of the Nine-Tails!" The other advisor, Homura, seemed fully prepared and maintained his aggressive stance. "Konoha cannot endure another Nine-Tails Incident, especially with the recent issues concerning Uchiha Shisui. Is Uchiha's clan unable to wait and has sent Anbu to their territory?"
"This matter probably has nothing to do with the Uchiha clan. I understand Guy's character; he's likely just acting recklessly. Don't overreact!" Sarutobi lifted his head sharply; he was shocked that they would dare mention Shisui and the Uchiha in this context. Wasn't that pouring gasoline on the fire?
"This isn't overreacting, Sarutobi! You still don't understand..." Homura was dissatisfied with Sarutobi's attitude and was preparing to emphasize just how precarious the relationship between the Uchiha clan and the Nine-Tails was.
"Bang!" The unmistakable sound of hurried footsteps echoed, and almost simultaneously, a green-clad Maito Guy burst into the Hokage's office, shouting, "Hokage-sama! I have urgent information... huh?"
"Guy?" Sarutobi, donning the Hokage robes, was momentarily taken aback. Upon realizing that only Guy had arrived, his expression grew serious. "Where's Naruto?"