Chapter 5 – Trust and Dependence Are Synonyms
"Lord Aizen."
"This is...?"
Just as Aizen was lost in thought, the boy standing behind him spoke up cautiously.
Kabuto Yakushi's gaze was fixed on the unfinished blade embryo in front of them. There was a trace of curiosity in his eyes, but deeper still lay a careful wariness—and an almost instinctive fear of touching upon something so secretive.
Kabuto had always been someone who knew how to read the times.
When he was with Root, he was the perfect assassin and spy.
At Orochimaru's side, he was the ideal agent and research assistant.
Later, when he was sent to Sasori, he became an impeccable double agent.
Wherever he went, whoever he served, Kabuto always found the position that best ensured his own survival.
And so, after Orochimaru's death—and with this man standing before him—Kabuto had very quickly accepted his new "captivity," and just as quickly chosen to display absolute submission.
"This is my research project, Kabuto."
Aizen's tone was light, as if he hadn't noticed Kabuto's caution at all.
"A weapon that can give form to the human soul."
"Though for now," he added with a faint smile, "it's still just a prototype."
The instant those words left his lips, Kabuto's chest tightened, though his face betrayed no change.
"A remarkable piece of research," he said smoothly.
"Is its core also made of Wood Release cells?"
"Strictly speaking, it's based on what I call the God Tree Factor—a name I've given to this unique property."
Aizen turned toward him, resting a palm lightly on the boy's head. His expression was calm and warm, as if entirely unaware of how much more deferential Kabuto had suddenly become.
"Kabuto," he asked gently, "do you know how chakra is produced inside a shinobi's body?"
"It is formed by the union of spiritual and physical energy," Kabuto answered promptly, lowering his head. His tone was flawless, betraying not a hint of hesitation—perfectly demonstrating his own value.
"Then tell me—why did shinobi only appear a thousand years ago?"
Kabuto paused, his voice faltering for the first time.
"Perhaps... because it took humanity thousands of years to accumulate the knowledge of the human body needed for such an evolution?"
Aizen shook his head, releasing him.
"No. It is because, until a thousand years ago, the human body did not even possess the chakra pathway system as an organ."
Kabuto's eyes widened in shock.
Impossible.
The chakra pathway system was the very first thing any student learned about at the academy—it was the foundation of all shinobi training.
Aizen continued, voice calm and unhurried:
"For years, I have dissected countless corpses—both shinobi and ordinary civilians. Every single one of them had a complete chakra network."
"But this organ is unique—it does not participate in blood circulation, nor does it interact with the nervous system. It exists only to transmit energy, as though it were... an outsider."
"This defies all known principles of evolution."
"And so, I began to wonder."
He turned away, his tone thoughtful.
"After poring over countless ancient records, I found a single common thread—a name: The God Tree."
Kabuto's heart skipped a beat, his expression growing more and more grave.
Aizen went on, voice soft but compelling:
"Then I connected it with the Wood Release once demonstrated by the First Hokage. As I dug deeper, the pieces began to fall into place."
He turned back to Kabuto, raising one finger as if he were a teacher guiding a promising pupil.
"Kabuto, did you know that in tropical and subtropical regions there exists a family of fully parasitic plants called Balanophoraceae?"
"They survive entirely by attaching themselves to their host, fusing with its vascular system to siphon nutrients and produce their own fruit."
"Some of these plants even secrete special signals to prevent insects from attacking their host, granting them a limited ecological benefit."
Kabuto's eyes widened unconsciously, a hint of horror creeping into his face.
"Lord Aizen... are you saying the chakra network is a kind of... parasitic plant?"
"I couldn't be sure before," Aizen said, turning back to the blade embryo.
"But after isolating several complete chakra systems from corpses and comparing them against Orochimaru's Wood Release cell samples, I discovered a striking genetic similarity."
"I call it the God Tree Factor."
"That ancient legend," he said quietly, "may truly be the origin of all chakra in this world. I believe even you have heard it before, haven't you, Kabuto?"
Of course Kabuto had heard the legend.
At the dawn of the world, the God Tree bore its fruit.
The goddess Kaguya Ōtsutsuki consumed it, gained the power to quell all war, and stood as a living god among men.
But over the long centuries, that goddess became something far more terrifying—an evil god without precedent.
In the end, the Sage of Six Paths rose up, defeated her, and sealed her away upon the moon.
It was the kind of myth every child in Konoha heard before they could even write.
But… was it really just a myth?
If it was all real—if those events truly happened—then…
Even imagining the scenes described in the legend sent a shiver down Kabuto's spine.
Just what kind of power could that possibly be?
Was that this man's goal—to recreate the power that had once existed only in myth?
The boy's thoughts twisted and tangled, becoming more complicated with each passing second.
And then, almost involuntarily, he found himself circling back to something Aizen had said before.
A parasitic plant.
A human host.
Drawing nutrients from the body.
And eventually—bearing fruit.
Kabuto blurted out before he could stop himself:
"If our chakra pathway system truly is a kind of parasitic organism… then… where are its fruits?"
Aizen turned his head slightly, as though considering the question, and replied softly:
"Yes."
"Where are its fruits?"
Kabuto froze, a sudden thought slamming into him. His mind snapped back to that ancient myth.
—The fruit eaten by the goddess.
The boy's entire body went rigid.
Seeing the stunned look on Kabuto's face, Aizen merely shook his head and turned his attention back to the blade embryo resting in its sealed chamber.
"In any case, the potential within this factor is not as limited as mere Wood Release. It contains far more possibilities."
"That is what I intend to keep exploring."
"What you see here—this blade—is merely a milestone, a product of that journey of inquiry."
"Next, I intend to weave the base logic of the Sharingan and the Byakugan into this weapon… Let's see whether the result is worthy of my expectations."
This was no whimsical experiment, but the culmination of countless searches and calculations.
Unlike the numerous bloodline limits scattered across the shinobi world—formed from endless combinations of chakra natures—there were only three that were truly ancient, truly primeval:
The unique vitality of the Senju clan.
The Sharingan of the Uchiha.
The Byakugan of the Hyūga.
All others were merely derivatives, branches born from the mingling of chakra attributes.
And those three? They shared a common origin.
The God Tree.
Or perhaps, the mysterious Sage of Six Paths and his brother, Hamura.
If that were the case… then reuniting those bloodlines should produce an astonishing result.
Aizen smiled faintly at the thought.
The only problem was that the resources, energy, and wealth required to carry out such a project were astronomical.
As a mere researcher, even one with the title of jōnin and a laboratory under the Hokage's tower, it was impossible to gather all of it quickly—especially the most important component, the Wood Release cells buried deep under Konoha's highest-level secrets.
That, in part, was why Aizen had set his sights on Orochimaru.
And also because, throughout the entire village, Orochimaru had been the only man who made him feel even a faint sense of caution—just as Kisuke Urahara once had.
But even now, a critical problem remained.
A true zanpakutō was created from a asauchi—a blank sword forged entirely of spirit particles—then imprinted with a Shinigami's soul, giving form to their inner world.
The God Tree Factor could serve as the vessel.
The ultimate form of the Sharingan—the Mangekyō—could replace the need for a soul's manifestation.
The Byakugan, with its unparalleled ability to merge with other bloodlines, would act as the perfect catalyst.
For that, Aizen would need at least one pure pair of Mangekyō Sharingan, and a significant number of Byakugan as the foundation for the experiment.
But there was still one thing missing—the spiritual root of the zanpakutō itself. No true substitute had yet been found.
Aizen, however, already had a few ideas.
While he pondered this, Kabuto finally seemed to shake off the impact of Aizen's revelations and quietly asked:
"But… Lord Aizen, why are you telling me all this?"
"I'm just an ordinary shinobi."
He didn't say the rest aloud—that only an hour ago, he had been Orochimaru's subordinate, freshly captured and dragged here. Why would this man trust him enough to share such secrets?
Kabuto didn't understand.
Nor could he know that Aizen had been watching him far longer than a single hour.
Aizen, unfazed, walked calmly to the desk at the center of the laboratory, sat down, and fixed Kabuto with a gentle look.
"Trust," Aizen said softly, "is just another word for dependence."
"And dependence… is the behavior of the weak."
"We don't need it."
"If it were me, I wouldn't ask you to trust me and walk beside me—I would simply ask whether you want to walk beside me."
"Do not trust anyone, Kabuto."
"Not even me."
He laced his fingers together and rested his hands on the desk, regarding the boy with eyes that were both calm and encouraging.
"So tell me…" Aizen's voice was warm, patient.
"Do you wish to follow me—and uncover the truth of this world?"
"Kabuto."
The words were simple, unadorned—yet they struck Kabuto like a kunai to the chest.
For a moment, he stood utterly still.
It felt as though someone had reached into him and touched the very deepest part of his soul.
In that moment, unbidden, an image surfaced in Kabuto's mind—the figure buried in his memory, the woman who had died without ever truly recognizing him.
His foster mother, Nonō Yakushi.
Do not trust anyone—and simply follow him?
...That would be ideal.
It was as if something inside him quietly loosened, and suddenly, Kabuto felt lighter than he had in years.
No loyalty.
No faith.
Only the pursuit of truth.
When he raised his head again and met Aizen Sōsuke's gaze, Kabuto's face broke into a bright, hollow smile—one so polished it seemed to fuse mask and face into one.
Then, without hesitation, he dropped to one knee, bowing low.
"Yes," he said solemnly.
"Lord Aizen."
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