After evolving Obito's Mangekyo Sharingan into the Eternal Mangekyo Sharingan, Shinji did not idle. He immediately used Susanoo Tomoshibi to evolve Shisui's and Hiruko's Mangekyo Sharingan into Eternal Mangekyo Sharingan as well, one by one.
With this, the number of Eternal Mangekyo Sharingan in Shinji's possession reached three pairs.
Tap, tap, tap...
Shinji propped his chin with one hand while tapping the ground lightly with the fingers of the other, mentally calculating his next move.
The Eternal Mangekyo Sharingan was only one step away from evolving into the Rinnegan. He was considering whether to spend some effort to evolve all three pairs of Eternal Mangekyo Sharingan into Rinnegan, or even Six-Tomoe Rinnegan.
However, he was also aware that evolving a Mangekyo Sharingan into an Eternal Mangekyo Sharingan only required enhancing the intensity of Yin Release chakra. But evolving an Eternal Mangekyo Sharingan into a Rinnegan involved the All Creation Power—the union of Yin and Yang.
There was a world of difference between the two!
Therefore, Shinji was not entirely certain if the Eternal Mangekyo Sharingan could be forcibly evolved into the Rinnegan through the fusion ability of Susanoo Tomoshibi.
Nevertheless, for many things, it is impossible to reach a conclusion without trying.
Shinji steadied his mind and activated Susanoo Tomoshibi once more, attempting to use its fusion ability to forcibly evolve Obito's pair of Eternal Mangekyo Sharingan, which contained Kamui, into the Rinnegan.
All Creation Power was extremely difficult for others to obtain—a precious power that could qualitatively enhance the intensity of one's chakra. But for Shinji, who had already advanced to Kekkei Mora, All Creation Power was readily available at his fingertips.
Thus, while activating the fusion ability of Susanoo Tomoshibi, he injected his own manifested All Creation Power into Obito's pair of Eternal Mangekyo Sharingan.
As the steady stream of All Creation Power was infused, Obito's Eternal Mangekyo Sharingan grew increasingly vivid, and an eerie light seemed to bloom upon the crimson pupils!
Yet, despite this, the patterns on that pair of Eternal Mangekyo Sharingan showed no change, let alone any signs of evolving into the Rinnegan.
Shinji frowned slightly and deactivated Susanoo Tomoshibi.
"The All Creation Power I injected was definitely sufficient for the Eternal Mangekyo Sharingan to evolve into the Rinnegan, so it's not a problem with the All Creation Power..."
"The pupil power of this pair of Eternal Mangekyo Sharingan shouldn't be the issue either..."
He ruled out the potential causes of failure one by one.
By the time he reached the end of his process of elimination, his expression gradually turned solemn, as if he had realized something.
Soon, he activated Susanoo Tomoshibi again, but this time he drove a pair of ordinary Three-Tomoe Sharingan.
He then used the fusion ability of Susanoo Tomoshibi to instill a large amount of high-quality Yin Release chakra into these Three-Tomoe Sharingan.
After a period of effort.
This high-quality Yin Release chakra—which was sufficient to evolve a Mangekyo Sharingan into an Eternal Mangekyo Sharingan—did nothing more than strengthen the pupil power of the Three-Tomoe Sharingan; it brought no other changes.
"As I suspected, it doesn't work!"
Shinji stopped Susanoo Tomoshibi once more.
Through this attempt, he had found the answer he was looking for: the Three-Tomoe Sharingan could not be forcibly evolved into the Mangekyo Sharingan through the fusion of Susanoo Tomoshibi. Much less could the Eternal Mangekyo Sharingan be evolved into the Rinnegan this way.
As for the reason, he had already faintly guessed it.
"The soul!"
The reason lay within the soul—or it could be understood as spirit, will, or something similar.
The Sharingan is essentially the "eye that reflects the heart." Without sufficient spiritual power and a unique will, it is impossible to evolve an ordinary Three-Tomoe Sharingan into a Mangekyo Sharingan. Even Shinji, who had become a Kekkei Mora, could not accomplish this for the time being!
This experiment also quelled his thoughts of mass-producing Mangekyo Sharingan and Rinnegan.
Of course.
Manufacture was still possible, but it would require significantly more effort. For example, by transplanting his Eternal Mangekyo Sharingan into direct descendants of Otsutsuki Indra or Otsutsuki Asura—such as members of the Uchiha, Senju, or Uzumaki clans.
Then, using these shinobi as living culture dishes, he could complete the chakra of Indra and Asura within them and use Yachihoko to inject a sufficient amount of All Creation Power to stimulate the transplanted Eternal Mangekyo Sharingan to evolve into the Rinnegan.
However, doing it this way meant mass production was impossible.
Because whether it was the Uchiha clan, the Senju, or the Uzumaki, the number of clansmen with pure bloodlines was already extremely scarce.
By Shinji's rough calculation, the only ones qualified to be living culture dishes were Obito (locked in a cell), Tsunade (the Hokage), and Naruto (the current reincarnation of Otsutsuki Asura).
As for others, either their bloodlines weren't pure enough or their strength was insufficient; they basically lacked the qualification to even serve as living culture dishes.
Shinji weighed his options and shelved this plan for the time being.
Primarily, even if he gained another pair of Rinnegan, the boost to his current strength would not be significant. Conversely, his time was extremely precious right now, and he had no budget to spend on a scheme with such low returns.
After suppressing the desire to create more Rinnegan, Shinji contemplated plans to continue enhancing his own strength.
At his current realm, the means to further increase his power were very, very limited.
Shinji carefully sorted through them and found that there were only three paths in total.
The first path was undoubtedly what all the Otsutsuki were doing: using the Divine Tree to pillage the energy of one planet after another, continuously condensing Chakra Fruits.
The second path was to activate the Infinite Tsukuyomi and absorb the chakra of the entire shinobi world into his own body, using quantitative change to force a qualitative leap!
The third path was to continue collecting high-level eyes!
Of course, the high-level dojutsu Bloodline Limits that the current Shinji would actually value were few and far between—he could count them on one hand.
As for the Shinjutsu research being conducted by Amado's research team, to be honest, Shinji was not certain if it could help him, or rather, if it would be completed in time to help him.
Because the time left by the Propagation Hegemon was only two to three years, and Shinjutsu was a power far surpassing ninjutsu or senjutsu. To expect results within just two or three years, even with all the geniuses of the shinobi world gathered together, was a great extravagance.
Shinji could lay the groundwork in advance, but he couldn't place too much hope on this matter; he couldn't use uncertain things to confront a Hegemon.