Uchiha Takashi set Fujiwara's affairs aside for the time being and began considering another question.
Most people in Uchiha Village were members of the Uchiha Clan. Although most were civilians, even civilian Uchiha could potentially awaken their eyes.
And the probability of awakening their eyes was tied to the concentration of their bloodline.
However, if the village's other residents were allowed to intermarry with Uchiha civilians, their bloodline concentration would certainly grow thinner with each passing generation.
Originally, everyone within the Uchiha Clan had been an Uchiha, so there had been no restrictions on marriage.
That would no longer work now. Other ordinary civilians were living alongside the Uchiha, so intermarriage with civilians was bound to happen.
Directly restricting the Uchiha Clan's marriages would undoubtedly reduce population growth, which would not be good for the clan either.
So Uchiha Takashi was considering how to purify the Uchiha Clan's bloodline without restricting intermarriage.
The Uchiha Clan valued their feelings deeply. If marriages were restricted, who knew how many incidents would arise over romantic relationships?
As everyone knew, the Uchiha bloodline originated from Otsutsuki Kaguya. The closer their bloodline was to hers, the purer it would be.
More precisely, they should draw closer to Indra. After all, Otsutsuki Kaguya possessed both yin and yang, while Indra alone was the source of the Uchiha's Yin Power.
Then how could he bring the Uchiha Clan's bloodline concentration closer to Indra's?
Rely on atavism? With those odds, getting even one in ten million would be lucky.
Rely on inbreeding? Come on, are you kidding me? The Uchiha Clan being this crazy was already a product of inbreeding.
If they went another round with inbreeding, Uchiha Takashi felt the odds of producing an idiot who could not even calculate 1+1 were far greater than those of producing a child who found calculus easy.
Cross inbreeding off the list. What other options were there?
Uchiha Takashi mulled it over until a name suddenly surfaced in his mind-the Chinoike Clan!
At that thought, Uchiha Takashi's eyes lit up.
The Chinoike Clan possessed the Ketsuryūgan, which was extremely similar to the Sharingan!
Both awakened through intense emotional fluctuations, and both provided a tremendous boost to genjutsu!
Uchiha Takashi had reason to suspect that this was the product of an illegitimate child ancestor Indra had left out in the world, whose bloodline had steadily thinned!
As everyone knew, all chakra in the Shinobi World originated from Otsutsuki Kaguya.
Then naturally, the Chinoike also came from Otsutsuki Kaguya, and their roots most likely lay in Indra's Yin Power as well.
If he could absorb this clan into the Uchiha, perhaps it would purify the Uchiha's yin bloodline to some extent and increase the probability of awakening their eyes.
At the same time, Uchiha Takashi also considered that the Sharingan's upper and lower limits were already fixed. Its ceiling was the Eternal Mangekyō Sharingan; the Rinnegan did not count, since it required combining with Yang Power.
The only possible difference was that the Mangekyō Sharingan's dōjutsu might vary, but even those differences could only go so far.
The only way to raise the Uchiha Clan's overall combat ceiling was to improve their base stats.
If the Chinoike Clan's Ketsuryūgan could be integrated into the Uchiha Clan, perhaps it could improve the Sharingan's base stats, raising the Uchiha Clan's theoretical floor and ceiling to some extent.
Put plainly, it was a high-grade fusion material that could greatly improve the Uchiha Clan's combat strength and bloodline concentration.
At least, that was what Uchiha Takashi believed. It would also provide a fallback.
Compared with the Sharingan, the Ketsuryūgan was more like an inferior substitute. If future clansmen could not awaken the Sharingan, perhaps they could try awakening a Ketsuryūgan instead.
If Uchiha Takashi remembered correctly, the Chinoike Clan was currently in the Land of Hot Water, and they did not seem to be doing very well.
With that in mind, Uchiha Takashi immediately wrote a letter to the grand elder, asking him to send someone to the Land of Hot Water.
In the letter, he described in detail how the Chinoike Clan might potentially enhance the Uchiha Clan's combat strength.
He hoped the grand elder could send people to the Land of Hot Water and absorb the Chinoike Clan into their ranks. Of course, if the other side refused to appreciate the gesture, they would have to resort to force again!
The grand elder soon sent a reply. Uchiha Takashi eagerly opened it, but its contents gave him a headache.
The grand elder's very first sentence was: "I suggest simply using force against the Chinoike."
As it turned out, the grudge between the Chinoike Clan and the Uchiha Clan was very, very deep!
According to the historical records left by their forebears:
In earlier years, the Uchiha and the Chinoike had both been mercenary clans based in the Land of Lightning.
Later, a woman from the Chinoike married the Daimyo of the Land of Lightning as his concubine, but the daimyo soon died of illness.
The principal wife was jealous of the concubine, so she falsely accused the Chinoike Clan of murdering the daimyo, while the new daimyo was her own child.
With the daimyo's support, the government paid to hire the Uchiha Clan as mercenaries.
They carried out the expulsion, driving the Chinoike Clan out of the Land of Lightning and into Hell Valley in the Land of Hot Water! They also accepted payment to help guard the Chinoike Clan.
Although the Uchiha later left the Land of Lightning for the Land of Fire, they had continued sending people to guard the Chinoike.
Even now, the Chinoike Clan still bore the charge of murdering the daimyo and remained imprisoned in Hell Valley.
Reading the words on the letter gave Uchiha Takashi a terrible headache. He had never expected such a deep grudge between the Uchiha Clan and the Chinoike Clan.
Seriously, the Chinoike's current misery seemed to be the Uchiha's doing. That made Uchiha Takashi's plans rather difficult to carry out.
Uchiha Takashi had originally thought that, since the Chinoike and the Uchiha were so similar, merging the two clans should be easy. Who could have expected such a heavy historical grudge between them?
This grudge already rivaled the one between the Uchiha and the Senju! The odds of a peaceful merger probably were not much better than those of making peace with the Senju.
That was also why the grand elder had directly advised Uchiha Takashi to use force.
Uchiha Takashi scratched his aching head. In that case, he could only prepare for both possibilities.
After all these years, how much hatred did the Chinoike still hold toward the Uchiha?
If they truly could not reach an agreement in the end, Uchiha Takashi would not mind using force.
Uchiha Takashi did not believe a clan that had been imprisoned for so long could still have the strength to challenge the Uchiha.
If they refused, he would simply have to beat them until they agreed. If the Chinoike Clan wanted to escape Hell Valley, they would have to agree to merge into the Uchiha.
(To supplement the setting a little, the original novels never mentioned who the Chinoike's ancestor actually was. However, because of their eyes' strong similarity to the Sharingan, many people consider them descendants of Indra.
They believe the clan resulted from the thinning and mutation of the bloodline of Indra's illegitimate child. However, this was never explicitly mentioned in the original work. Indra had only the Uchiha; otherwise, his reincarnations would not have been born into the Uchiha generation after generation.
But here, the author has personally set them as descendants of Indra's illegitimate child. As for how to explain why Indra keeps reincarnating among the Uchiha, let us chalk it up to their bloodline concentration being too low.
Please note that this is not part of the original setting. It is the author's own setting, just to fill in the logic.)