One month passed swiftly.
Within the serene Miko's Palace in the Land of Demons, deep inside an underground secret laboratory he had been granted access to, Tatsuya was engrossed in a delicate experiment at a large, metallic operating table.
A newly cultivated clone body lay motionless on the table's surface. Tatsuya leaned over it, carefully, meticulously inscribing an intricate, newly designed sealing formula onto its inert skin. This private laboratory space had been specifically requested by Tatsuya from the Miko for his research. The clone itself wasn't created here; it had been cultivated remotely by Jizo back in their Konoha facility and subsequently transported instantaneously to this location via Tatsuya's use of the Summoning Technique.
A full month had now elapsed since the Miko had generously transmitted the vast repository of her lineage's fuinjutsu knowledge directly into Tatsuya's mind. During this intensive month of study and analysis, utilizing the powerful processing capabilities of his internal bio-chip, Tatsuya had thoroughly dissected, analyzed, and completely grasped the fundamental principles underlying the Miko lineage's unique sealing techniques.
Having processed all the transmitted information, Tatsuya now fully understood the underlying reason why the Miko had agreed so readily to share her supposedly sacred lineage's fuinjutsu with an outsider like him. He realized that the core techniques, the most powerful applications, required the user to possess the Miko lineage's specific, innate telepathic or empathic abilities to perform effectively and safely. Without that unique hereditary gift, others simply couldn't utilize the most advanced forms of her fuinjutsu.
However, Tatsuya wasn't particularly concerned about this inherent limitation. His primary goal in seeking to learn the Miko's fuinjutsu hadn't been to replicate her ability to seal the demon Mōryō himself. Rather, his aim had been far more specific: to extract the underlying theoretical principles, the foundational knowledge of soul manipulation and energy containment, that could be adapted and repurposed for his own ambitious projects.
He had already thoroughly achieved that objective. After storing the entirety of the Miko lineage's fuinjutsu knowledge, the bio-chip had meticulously analyzed and synthesized the vast dataset. From this analysis, Tatsuya had successfully derived exactly what he needed: a set of fundamental sealing formulas capable of effectively restricting spiritual bodies – souls.
Using these foundational formulas as a conceptual basis, the bio-chip had then spent the latter half of the month running complex simulations and developing a unique, derived sealing technique designed specifically for the purpose of sealing and controlling souls.
Tatsuya had designated this new, custom fuinjutsu: the Soul Seal
The intended function of the Soul Seal bore some superficial resemblance to the infamous Reaper Death Seal technique, in that it targeted the soul directly. However, whether his newly created Soul Seal possessed sufficient power to successfully seal overwhelmingly powerful spiritual entities, such as the Yin-half of the Nine-Tails for instance, remained entirely unknown for the time being. That would require further testing.
Which brought him to his current activity. What Tatsuya was doing now was carefully inscribing the finalized matrix of the Soul Seal onto a fresh clone body – one specifically cultivated to lack any independent consciousness – preparing to conduct the initial tests of the seal's basic effects and stability.
He acknowledged, at least internally, that such experiments involving clones, even non-sentient ones, arguably violated certain commonly accepted principles of human ethics. However, for testing a technique designed to interact directly with a soul, Tatsuya felt he had few safer or more effective alternatives available to him. To mitigate this ethical gray area somewhat in his own mind, the clone body being used for this particular crucial experiment had been cultivated solely and exclusively from Tatsuya's own genetic material. In a very real, tangible sense, the body on the table was fundamentally just another 'Tatsuya'.
Tap, tap, tap...
The soft sound of approaching footsteps echoed from the corridor outside the secluded laboratory. Soon, the door slid open, and the gentle, graceful, and beautiful Miko entered the room.
"Tatsuya-kun," she greeted him warmly, then tilted her head slightly, her gaze falling curiously upon the clone body laid out on the operating table. "What is this fascinating research you are conducting here?"
"Ah, Your Highness," Tatsuya looked up, his expression genuinely excited. He gestured towards the clone on the table. "It is only thanks to Your Highness's incredible generosity in sharing your lineage's profound knowledge that I was able to successfully develop this particular sealing technique! I was just preparing to test its initial effects."
As he turned his head to look directly at the Miko standing serenely beside him, a peculiar, almost calculating glint flickered briefly deep within Tatsuya's eyes. Through the vast amount of contextual and perhaps unintentional background information transmitted directly into his mind via the Miko's Mind Jutsu a month prior, Tatsuya had inadvertently glimpsed certain hidden truths, fragments of secrets pertaining to the Miko lineage itself. If his bio-chip's subsequent analysis of certain subtle energy patterns and historical data points embedded within that transmission was accurate... it seemed the remaining natural lifespan of this kind, gentle, and seemingly young Miko before him was already tragically short.
It appeared, Tatsuya had deduced, that the Miko of the Land of Demons were intrinsically, perhaps even fatedly, bound to the cyclical existence of the demon Mōryō. The ultimate, unavoidable price for performing the powerful sealing ritual required to contain Mōryō, the ritual she had just recently performed, was the gradual expenditure of the Miko's own life force, her remaining years. He recalled again, with certainty now, that in the original timeline he remembered, this particular Miko – Miroku – had indeed perished as a direct result of sealing the demon, leaving her young daughter Shion to inherit the burden alone.
It was precisely because Tatsuya was now aware of these potential future events, this inherent sacrifice woven into the Miko's duty, that he hadn't deliberately concealed his clone-based experimentation activities from her. He felt a strange sense of connection, perhaps even obligation, given what he knew.
"Tatsuya-kun," the Miko asked, her curiosity piqued as she observed the intricate seal pattern on the clone after a moment, "what is the name of this sealing technique you have developed? And what exactly is its intended effect?"
"This sealing technique is called the Soul Seal, Your Highness," Tatsuya explained directly, deciding on transparency. "Its primary function is to effectively seal and restrict the target's soul, its spiritual essence." Given the Miko's innate telepathic or empathic abilities, Tatsuya saw little point or wisdom in attempting deception. Furthermore, he recognized that within the unique political landscape of the Land of Demons and the Land of Swamps, there was effectively no higher temporal or spiritual authority than the Miko's word. Earning her genuine trust and potential cooperation was crucial for the smooth execution of his ambitious future plans.
"Restricting souls?" A look of deep unease, almost pity, crossed the Miko's gentle face upon hearing his blunt description. "Is it... akin to becoming an enslaver of spirits?"
"Something functionally similar to that, yes," Tatsuya confirmed with a neutral nod, not shying away from the darker implications.
"And for what purpose do you intend to utilize such a morally complex technique, Tatsuya-kun?" the Miko pressed gently but firmly, her gaze searching his own, perhaps probing his intentions with her unique senses.
Tatsuya paused for a thoughtful moment before revealing his true, audacious goal. "I intend," he stated calmly, deliberately, "to create an artificial Tailed Beast."
"An Artificial Tailed Beast?" The Miko looked utterly perplexed, clearly unfamiliar with the concept.
A fervent, almost obsessive gleam suddenly lit up Tatsuya's eyes as he elaborated. "Exactly. It is the core component of my 'Artificial Tailed Beast Plan'. Consider this, Your Highness – hypothetically speaking, what might the implications be if I were capable of successfully sealing an existence possessing immense power, perhaps even comparable to Mōryō, within my own body, yet maintaining full control?"
"What?!" The Miko recoiled, her eyes widening in genuine shock and undisguised horror at his suggestion. "Tatsuya-kun, such thoughts are far too reckless and terrifying! No human mind, no matter how strong, could possibly withstand the full psychic assault of Mōryō's overwhelming evil will if contained so closely! You would inevitably lose yourself and become nothing more than a mindless puppet controlled by the demon!" she pleaded urgently, trying to dissuade him from what sounded like a suicidal path.
"Please rest assured, Your Highness!" Tatsuya quickly interjected, seeing her genuine alarm and realizing his example had been poorly chosen. "I was merely posing a conceptual, hypothetical scenario to illustrate the potential scale. I am well aware of the extreme danger posed by Mōryō's malevolent consciousness; I experienced it directly, after all. I am certainly not arrogant enough to attempt such a foolish thing myself," he reassured her sincerely. "The specific 'existence' I spoke of potentially sealing for my plan... it is not Mōryō."
The Miko still looked deeply skeptical, her earlier unease returning. "Tatsuya-kun," she asked pointedly, her gaze narrowing slightly, "if that is true, then why did you previously ask my assistance in securing a personal fiefdom for yourself located specifically near Demon Sealing Mountain in the Land of Swamps? Your explanation seems... contradictory." She clearly didn't fully believe his quick denial, her sharp mind connecting his stated interest in Mōryō's energy with his desire for proximity to its prison. In the known shinobi world, besides the nine original Tailed Beasts themselves, what other readily accessible existence could possibly rival the sheer power contained within Mōryō? And, she reasoned further, if one simply wished to become a Jinchūriki for one of the existing Tailed Beasts (a dangerous enough prospect on its own), there seemed little logical necessity for Tatsuya to go to the extreme lengths of developing a completely new, specialized soul-restricting fuinjutsu like the Soul Seal. Standard Jinchūriki sealing methods already existed.
"Your Highness, my request for land near Demon Sealing Mountain is genuinely intended, as I stated, for conducting contained experiments utilizing the unique ambient energies that naturally radiate from the sealed demon's proximity," Tatsuya explained patiently, maintaining his composure. "It is not part of any plan to attempt to seal Mōryō itself within me, I assure you." He paused, then decided to reveal his true target. "The specific existence I actually plan to utilize for my Artificial Tailed Beast project... is the legendary Dragon Vein, sealed beneath the ruins of the ancient kingdom of Rōran," Tatsuya revealed with a calm, confident smile.
(Tatsuya had, of course, already personally experienced Mōryō's overwhelming evil will firsthand during the psychic assault; even if he somehow possessed the technical means to successfully seal the full demon within himself now, he had absolutely no desire or intention of carrying such a fundamentally malevolent and corrupting entity around within his own being. Tatsuya was ambitious, but not blindly arrogant about his mental fortitude or his ability to resist such constant, insidious influence indefinitely. Under the long-term, pervasive influence of Mōryō's potent evil intent, he knew, anyone's personality and core nature would inevitably, irrevocably change, almost certainly for the worse.)
"The Dragon Vein... of ancient Rōran?" Hearing this specific, legendary name, the Miko's expression immediately shifted, perplexity replaced by sudden, dawning understanding. The immense power source known as the Dragon Vein of Rōran had indeed once been a famously powerful, albeit volatile, entity in the shinobi world's distant history; the Miko, as a keeper of ancient lore, was certainly aware of its legends. Furthermore, she knew the hereditary lineage of the Queens of ancient Rōran, who were intrinsically tied to the Dragon Vein, shared certain esoteric similarities with her own Miko lineage. According to those same ancient legends, only the Queens of Rōran possessed the unique, specific ability required to perfectly seal and safely control the immense, chaotic power of the Dragon Vein.
"However," the Miko continued, her brow furrowing slightly in renewed confusion as she considered the implications, "ever since the tragic fall of the ancient kingdom of Rōran countless ages ago, all traces of both the Dragon Vein itself and any surviving members of the Rōran Queen lineage have seemingly vanished completely from the shinobi world." She looked at Tatsuya searchingly. "Tatsuya-kun, as far as all known legends tell, only the Queen lineage of Rōran possesses the key to truly sealing the Dragon Vein. Your newly developed 'Soul Seal', however ingenious, likely wouldn't be capable of containing such a unique and immense power source properly on its own." She paused, then added another practical objection. "Furthermore, Tatsuya-kun... given your already considerable personal power demonstrated through Sage Mode and your other abilities, it seems... somewhat unnecessary, perhaps even excessively risky, to go to such potentially great lengths and trouble to try and harness the power of the notoriously unstable Dragon Vein, doesn't it?"
"Your Highness may not be fully aware of the current situation," Tatsuya began, choosing his words carefully again, "but I have previously conducted a personal investigation regarding the Dragon Vein of Rōran. I have already successfully located its sealed resting place." He continued, "Due to the natural erosion of countless intervening years, the original ancient seal containing the Dragon Vein has weakened quite significantly. From a purely technical fuinjutsu standpoint, unsealing it and subsequently resealing it within a prepared vessel should not be overly difficult." He leaned in slightly, emphasizing his next point. "The real, fundamental challenge, Your Highness, lies not in the initial sealing process itself, but in what comes after successfully sealing such a potent entity within a host body: how does one effectively restrict and safely control the Dragon Vein's own powerful, already-developed, independent consciousness?" He smiled confidently. "That specific, crucial problem is precisely what my Soul Seal technique is designed to solve."
(One absolutely vital detail Tatsuya deliberately did not explicitly mention to the Miko at this juncture was that he knew for a fact, based on his past life's knowledge, that direct descendants of the ancient Rōran Queen lineage still existed in the present day, albeit hidden. This secret knowledge was the true, unstated key to Tatsuya's confidence in being able to both safely unseal the Dragon Vein when the time was right, and subsequently successfully reseal it within a suitable host – most likely, one of his own specially prepared clone bodies.)
"I see..." the Miko murmured, nodding thoughtfully as she processed Tatsuya's intricate explanation, his logic seeming plausible given the context he provided. The concept of controlling a sealed entity's consciousness was indeed a novel challenge beyond simple containment.
After several moments of quiet, careful contemplation, she looked up at Tatsuya again, her expression clearing as she seemed to reach a decision. A bright, genuine smile finally graced her lips. "Ah, by the way, Tatsuya-kun," she said, changing the subject slightly, "regarding that fiefdom you requested near Demon Sealing Mountain... consider it fully arranged."