"Rinnegan!"
At the thought of the Rinnegan, Uchiha Fugaku's eyes burned with desire.
The Rinnegan was one of the strongest dōjutsu in existence — an eye technique of the highest order.
This was proven in the original timeline, where Nagato, relying solely on a transplanted pair of Rinnegan, destroyed Konoha — one of the Five Great Ninja Villages — in a single strike, leaving the village utterly helpless.
And that wasn't even the Rinnegan's full potential.
After all, transplanted eyes couldn't perfectly merge with the body, meaning their true power was far below what their original owner could unleash.
"Let's check the abilities of this Mangekyō."
He searched through Fugaku's memories to confirm its powers.
This Mangekyō would become his greatest trump card for now, so he needed to understand it thoroughly.
"The right eye's ability is Real Illusion."
His eyes brightened slightly.
Real Illusion was a dōjutsu similar to Uchiha Itachi's Tsukuyomi.
Like Tsukuyomi, it created an illusionary space — but unlike Tsukuyomi, any damage inflicted within that space would be reflected onto the victim's real body.
For example, if the enemy were slashed by a blade inside the illusion, an identical wound would appear on them in reality.
That ability to turn illusion into physical harm was why it was called Real Illusion.
"An illusion stronger than Tsukuyomi."
In Fugaku's view, Real Illusion far surpassed Tsukuyomi.
Tsukuyomi inflicted only mental trauma, while Real Illusion directly damaged the body — clearly a higher-tier technique.
"The left eye's ability is Corpse Fusion."
After examining his right eye, he turned his attention to the left — and his pupils instantly ignited with excitement.
Corpse Fusion was an extraordinarily rare and terrifying dōjutsu.
It allowed him to fuse the corpse of a recently deceased person into his own body, gaining that person's talent in genjutsu, taijutsu, ninjutsu, and more.
If the target possessed a bloodline limit, he could even transform that bloodline into his own.
It didn't disappoint him — the left eye's ability was no weaker than the right, and in some ways, its value was far greater.
"What a waste… sitting on a treasure mountain without knowing how to use it."
After reviewing Fugaku's past usage — or rather, lack of usage — of this ability, he couldn't help but feel disdain.
In Fugaku's view, as head of the Uchiha clan, his talent in ninjutsu, taijutsu, and genjutsu already surpassed most others.
The Sharingan was the strongest bloodline limit, and those of other clans were far inferior.
Because of that arrogance, Fugaku had dismissed Corpse Fusion as useless and never once activated it.
In Fugaku's eyes, this was nothing short of foolish.
No wonder the Uchiha clan had ultimately met extinction.
It could be said that their downfall was closely tied to Fugaku's weakness and rigidity.
"With Corpse Fusion, my chances of obtaining the Rinnegan are much higher!"
Excitement surged through him.
To awaken the Rinnegan, two conditions were required.
First: transplanting a genetically compatible pair of Mangekyō Sharingan.
Uchiha Itachi's Mangekyō was perfectly suited for this — given their blood relationship, the chances of evolving into the Eternal Mangekyō Sharingan after transplantation were extremely high.
As for his superficial father–son relationship with Itachi… since the boy wanted to kill him anyway, why should he care?
Leaving Itachi alive would already count as mercy.
The real difficulty lay in the second condition: transplanting Hashirama's cells.
Hashirama cell transplantation carried enormous risks. One mistake could cause rejection, mutation, or even complete assimilation by the cells.
And even after a successful transplant, perfect fusion wasn't guaranteed.
In the original timeline, after Uchiha Madara implanted Hashirama's cells, it took him decades — until the brink of death — to finally awaken the Rinnegan.
Fugaku believed that delay occurred because the cells never fully integrated with Madara's body.
But if he used Corpse Fusion to fuse with someone whose body had already perfectly assimilated Hashirama cells, not only would he gain those cells — they would merge flawlessly with him.
That would drastically shorten the time required to awaken the Rinnegan.
"And not just the Rinnegan… I could use this to obtain bloodline limits no weaker than it."
His heart raced.
Without Corpse Fusion, even with foreknowledge, his ultimate achievement would probably stop at the Rinnegan.
That alone would guarantee survival — but it wouldn't allow him to challenge the Ten-Tails or Ōtsutsuki Kaguya.
But with Corpse Fusion, everything changed.
He could acquire other bloodline limits on par with the Rinnegan.
For example — the Tenseigan, the dōjutsu passed down by Ōtsutsuki Hamura, the Sage of Six Paths' younger brother.
He knew exactly how it was born.
The Byakugan of the Hyūga clan, combined with the chakra lineage of Ōtsutsuki Toneri from the Moon — that was the method.
By fusing their corpses using Corpse Fusion, he could theoretically awaken the Tenseigan himself.
"If I can possess both the Rinnegan and the Tenseigan… even Ōtsutsuki Kaguya wouldn't be invincible."
Anticipation surged through him.
Both eyes were supreme dōjutsu — possessing both would elevate him to an entirely different plane of existence.
After all, the Sage of Six Paths and Ōtsutsuki Hamura had only been able to seal Kaguya together.
If he wielded both of their powers in one body, why couldn't he do the same?
"What a waste… truly sitting on a treasure mountain without knowing how to use it."
Once again, he lamented Fugaku's foolishness.
To possess such a terrifying ability and fail to exploit it — no wonder the Uchiha clan was destroyed.
Of course, this was also because Fugaku lacked foresight. He didn't know the methods for awakening the Rinnegan or the Tenseigan.
Corpse Fusion could only reach its true potential in the hands of someone like him.
For anyone else, at most, it would allow them to collect multiple bloodline limits — strong, yes, but nowhere near the qualitative leap of awakening supreme dōjutsu.
"Fugaku, dinner's ready."
A soft knock came from outside, followed by Uchiha Mikoto's gentle voice.
"Coming."
Fugaku replied as he opened the door and stepped out of the study.
Now that he had found a path to power, the anxiety that had plagued him since transmigrating finally eased.
The future was no longer hopeless.
He had found his "golden finger" — not one granted by fate, but one his predecessor had possessed all along.