Returning to his secret laboratory, Shinji descended to the underground training area within the facility.
Standing in the center of the unlit training ground, in the darkness, he slowly opened his eyes, revealing the scarlet pupils within his sockets.
On his pupils, the tomoe spun rapidly, connecting like black threads to form a complex, angular pattern.
"Susanoo…"
With a low whisper from Shinji, a golden phantom projected from his body—starting with bones, then meridians, followed by muscles, and finally clad in armor. In an instant, a towering golden half-body armored giant appeared in the training area, dispelling the surrounding darkness!
Sensing the power, Shinji's lips curved into a smile.
With his current level of dojutsu power, maintaining the most taxing Mangekyō technique, 'Susanoo,' was no longer a burden.
Steadying himself, he activated his Mangekyō dojutsu, 'Susanoo Tomoshibi.'
Roar.
In an instant, the golden 'Susanoo' enveloping Shinji let out a roar. Its faceplate peeled away, revealing three pairs of eye sockets on its face!
Shinji took out the small nutrient canister containing the 'Koryugan' and removed the pair of eyes that seemed both gem-like and fleshy.
Holding the 'Koryugan' in his palms, he activated 'Susanoo Tomoshibi' again, removing the pair of Ketsuryugan from the third eye socket and replacing them with the 'Koryugan.'
"Phew."
After swapping the third pair of eyes for the 'Koryugan,' he closed his own eyes, focusing entirely on sensing the changes.
"Hmm?"
Moments later, he let out a soft exclamation.
Compared to when he had previously wielded the 'Koryugan,' its dojutsu power now seemed stronger, faintly approaching the level of an ordinary Eternal Mangekyō Sharingan.
The increase in dojutsu power was secondary. What truly shocked Shinji was that the 'Koryugan's' ability to enhance the soul was two to three times stronger than when it was first fused.
Shinji opened his eyes and murmured, "As expected…"
To create the 'Koryugan,' he had used up a total of five pairs of Ketsuryugan and two pairs of Hogan, including those wasted in the process.
When he finally fused the 'Koryugan' using 'Susanoo Tomoshibi,' he had a feeling that its full potential hadn't been revealed.
This was why he chose to transplant the 'Koryugan' into Yakumo, using her to further explore its capabilities.
He hadn't expected the 'Koryugan' to have such immense potential. After being nurtured and developed by Yakumo, not only had its dojutsu power continued to grow, but its abilities had also become several times stronger than at the time of fusion—especially its soul-enhancing capability, which left Shinji astounded.
He discovered that his chakra reserves had doubled after wielding the 'Koryugan.'
"I understand now. Training the 'Twelve Palaces' has coordinated my body's organs, further unlocking the potential of this body! After successfully wielding the 'Koryugan,' my spiritual body was greatly enhanced, leading to a significant boost in my mental strength!"
Chakra is the product of combining physical and mental energy, so a mere increase in physical strength wouldn't significantly impact chakra reserves.
But when Shinji wielded the 'Koryugan,' with his soul greatly enhanced, both his physical and mental energies surged, causing his chakra reserves to skyrocket to a level he hadn't anticipated.
Suddenly, another thought struck him, and he quickly activated 'Jikibi.'
Moments later, the smile on his face grew wider.
He discovered that the sensory range of his 'Jikibi' had expanded from a 100-kilometer radius to a 150-kilometer radius.
"This must be the result of my enhanced soul strength and increased dojutsu power! Truly unexpected—the 'Koryugan' has given me such a pleasant surprise!"
Experiencing the power of the 'Koryugan,' Shinji's demeanor gradually shifted.
Setting aside everything else, the soul-enhancing ability alone made the 'Koryugan's' value incalculable.
"If that's the case, the 'Koryugan' can't simply be considered a lesser dojutsu Bloodline Limit compared to the Rinnegan or Byakugan!"
With a deeper understanding of various dojutsu Bloodline Limits, Shinji realized his previous classifications had flaws.
He now believed dojutsu Bloodline Limits could be roughly divided into three tiers.
The first tier consisted of basic dojutsu Bloodline Limits, including the ordinary Byakugan, tomoe Sharingan, Ketsuryugan, and Hogan.
The second tier included unstable advanced dojutsu Bloodline Limits, currently represented only by the Mangekyō Sharingan.
The third tier comprised stable advanced dojutsu Bloodline Limits, including the Rinnegan, Byakugan (in its Tenseigan form), and Eternal Mangekyō Sharingan.
Previously, he had placed the 'Koryugan' in the second tier, alongside the Mangekyō Sharingan.
Now, he believed the 'Koryugan' belonged in the third tier, on par with the Rinnegan, Tenseigan, and Eternal Mangekyō Sharingan.
Deactivating 'Susanoo,' Shinji returned to the laboratory with light steps.
The unexpected boon of the 'Koryugan' doubling his chakra reserves gave him greater confidence in surviving the First Hokage cell transplant surgery.
The more chakra he had, the better he could withstand and integrate the domineering Yang Release chakra contained in the First Hokage cells.
Approaching the operating table, Shinji began preparing for the surgery.
Monitoring equipment for vital signs was, of course, essential. After calibrating the devices, he retrieved an optimized fusion agent from the refrigeration unit.
This fusion agent was an enhanced version of Tsunade's formula, secretly prepared by Shinji months ago.
After completing these preparations, Shinji moved to the petri dishes.
Before implanting the First Hokage cells, he needed to activate them, ensuring their activity reached a certain level to guarantee the surgery's effectiveness.
Once everything was ready, Shinji sat on the operating table.
At his side, two syringes were neatly arranged: one containing the activated First Hokage cells, the other holding the optimized fusion agent.
As for suppressants, he hadn't prepared any this time.
Suppressants traded surgical effectiveness for increased survival rates.
Yamato's case was a clear example: excessive use of suppressants significantly boosted survival rates, but the post-surgery results were lackluster. As a 'Wood Release' shinobi, Yamato couldn't compare to the First Hokage, or even to Yakumo, in terms of Wood Release potency.
Clearing his mind of distractions, Shinji picked up the syringe containing the First Hokage cells.