After testing his current body with various ninjutsu, Kurogane Ren's satisfaction only grew. Not only could he use techniques more frequently, but their power had also increased dramatically. It reminded him of Six Paths Naruto and Six Paths Sasuke; even without complex mechanics, Naruto's attacks hit with absurd force, a pure expression of overwhelming stats. There was nothing surprising about it. With the same level of mastery, the more chakra poured into a technique, the stronger it became. Of course, every jutsu had its limit. Once that ceiling was reached, adding more chakra made no difference.
Once the tests were complete, Kurogane Ren moved to another set of cultivation tanks, staring at the bloodline samples he had gathered during the Second and Third Shinobi Wars. Given enough time, he would have preferred to complete further fusions before returning to Konoha, but that would take too long. He might miss the moment when Nohara Rin was captured.
To stay safe, every additional bloodline required testing before he could risk fusing it into his own body. As the number of fused bloodlines increased, the difficulty would rise exponentially. By the time Beluhu reached five bloodlines, he had waited years for the perfect alignment of Heaven, Earth, and Man. That alone proved how dangerous each step was. Kurogane Ren simply didn't have the luxury of time to safely experiment with a second fusion.
His gaze settled on one of his key materials: a corpse bearing a single-tomoe Sharingan.
Yes, his second target was the Uchiha bloodline.
This specimen was the only one he had managed to acquire that had actually awakened the Sharingan, and even then, it was only a single tomoe. He had collected plenty of Uchiha bodies without awakened eyes, which had been relatively easy given his role as a sealing specialist responsible for handling fallen shinobi. Swapping bodies with fakes had allowed him to quietly secure these materials.
But obtaining a Sharingan user was far more difficult. Every awakened Uchiha was recorded and monitored. Even the notoriously careless Uchiha clan would notice if one went missing. This particular specimen had only awakened its Sharingan at the moment of death, which made it possible for Kurogane Ren to take it unnoticed.
As everyone knew, the Sharingan awakened under intense emotional stimulation. Facing death was one of the strongest triggers. Still, even then, such awakenings were rare.
Truthfully, Kurogane Ren could accept not having a Sharingan. Unlike other bloodlines, it could be awakened later or even transplanted. But if he could naturally awaken it, that would be far better.
A thought suddenly crossed his mind. If he didn't fuse the Uchiha bloodline but only fused the Uzumaki bloodline, could he freely activate and deactivate the Sharingan? After all, the Uzumaki and Uchiha shared a common origin.
But recalling examples like Danzo, who had both Sharingan and Hashirama cells yet still couldn't control the activation freely, Kurogane Ren shook his head. The Uzumaki lineage, as an offshoot of the Senju, likely wouldn't grant that ability either.
In that case, the Uchiha bloodline was essential. The Sage of Six Paths' power had split into the Sage Body and Sage Eyes. Only by combining both could one reach true perfection. Just as Uchiha Madara had fused Hashirama's cells to awaken the Rinnegan, Kurogane Ren knew both aspects were indispensable. There was no point in trying shortcuts.
His attention then shifted to another set of materials: the Hyuga bloodline.
Here, he hesitated.
All the Hyuga samples he possessed were from the branch family. While genetically they weren't significantly inferior to the main family due to intermarriage, the problem lay with the Caged Bird Seal. Kurogane Ren couldn't confirm whether the seal would persist after death.
In the original story, Neji's Caged Bird Seal disappeared upon his death. However, when Hizashi was revived through Edo Tensei, the seal was still present. That raised too many uncertainties. Was the seal truly gone after death, or was there some other factor at play?
If he fused the Hyuga bloodline and inherited the Caged Bird Seal, it would be disastrous.
Yet giving up on the Hyuga bloodline was equally unacceptable. It represented the potential to evolve into the Tenseigan, a power on par with the Rinnegan.
Kurogane Ren stared at the forehead of the corpse before him, which bore no visible seal, and fell into deep thought.
Obtaining main family blood was impossible. The Hyuga clan guarded it with obsessive vigilance. Even on the battlefield, outsiders were never allowed near their corpses.
That left him with one option: experimentation.
He would fuse the Hyuga bloodline into test subjects and observe whether the Caged Bird Seal manifested over time. Alternatively, he could attempt to alter the seal's placement through future refinements. After all, he didn't need the Byakugan itself, only the bloodline.
And even if he wanted the Byakugan, it would be useless. The moment a branch family member died, both their brain and Byakugan were destroyed by the seal.
Of the two approaches, the second one seemed viable immediately.
A glint flashed in Kurogane Ren's eyes. Without hesitation, he used the Demonic Statue Fusion Technique to merge several Hyuga bloodline samples into test subjects, then sealed and restrained them before placing them back into containment.
Now, all that remained was time.
If no Caged Bird Seal appeared after prolonged observation, that would be his answer.
He wasn't in a hurry. The fourth and fifth bloodlines he had in mind would take a long time to acquire anyway.
And that time… would be more than enough for verification.