The Mangekyō Sharingan was very similar to a Stand.
Both were projections of the mind that appeared in the real world after one's inner desires and obsessions had condensed to an extreme degree within the subconscious.
Living through the Uchiha clan's difficult times, Itachi Uchiha longed to create, through his own strength, a wonderful world where everyone could live in harmony. Thus, he gained the ultimate genjutsu second only to Kotoamatsukami—
Tsukuyomi.
And because he knew that such beauty could exist only within an illusion, Itachi's other eye held the flames of Amaterasu, which yearned to destroy and burn everything away.
He wanted to create new life from the ashes.
That was Itachi's belief.
It also explained why he had supported Nagato's Tailed Beast weapon plan back then.
As for Fugaku Uchiha, he was an extremely conflicted man.
On one hand, he was a member of the Uchiha clan—a backbone and elite in his youth, then the clan head in his later years.
On the other hand, he was a husband and father.
Thirdly, he was a ninja of Konoha.
Clan, family, and village—ever since Fugaku Uchiha had been born, the three had been intertwined. Loyalty, filial piety, and righteousness were difficult to balance.
Unlike Itachi, who either wanted to create an illusory world or destroy everything.
What Fugaku Uchiha desired was a narrow path through the tangled chaos of conflicting interests, one where everyone could survive.
Thus, Fugaku's Mangekyō Sharingan was called—
"Ame-no-Futodama-no-Mikoto."
This was a Mangekyō ability that no one had ever known about. Only Itachi Uchiha had witnessed it once, on the eve of Fugaku's decision to launch the coup.
Its ability was:
"Deduction," something close to precognition.
Once Ame-no-Futodama-no-Mikoto was used on a designated target, it could obtain a vast number of information fragments related to