PS: This one's a little short because I have to be a groomsman and rush back and forth, so I could only write this much. I'll make it up later, though—that's Xiao Ye's promise! Please don't worry, dear readers.
"What? There's a way to completely eliminate the side effects of the Mangekyō Sharingan?"
Naruto's words.
Without a doubt, they stirred up a storm in the depths of Sasuke and Itachi's hearts. The Sharingan was the Uchiha Clan's greatest secret. In its ordinary tomoe form, it merely consumed a fairly large amount of the user's chakra, but the Mangekyō Sharingan was different. Every time it was used, it not only placed an enormous physical burden on the user, but also consumed eye power that was nearly impossible to restore. No matter how sparingly it was used, the eye power of an ordinary Mangekyō Sharingan would eventually run out. When that happened, the user was destined to go blind. This was an irreversible truth passed down through generations of the Uchiha Clan. The only solution their descendants knew was to fuse two pairs of Mangekyō Sharingan and evolve them into the Eternal Mangekyō Sharingan. Only then could the burden these evil eyes placed on the body be greatly reduced and the side effect of eye-power depletion be eliminated entirely. Put simply, as long as you had unlimited chakra, you could use these eyes indefinitely.
Throughout the history of the Uchiha Clan,
there had only ever been one example: Uchiha Madara.
This was the Uchiha Clan's greatest secret.
Sasuke had only learned about it from his brother recently.
But now, from Naruto, the brothers Itachi and Sasuke had learned of another way to avoid the physical burden caused by an ordinary Mangekyō Sharingan. Needless to say, Naruto's words had deeply shocked them both.