Shisui was lauded by the Uchiha clan as having the most powerful genjutsu in the clan, Kotoamatsukami. This genjutsu, to put it in video game terms, is COMPLETELY BROKEN. It’s past the point of op and going basically into “tgm”, god mode (where you don’t even take fall damage, even if you fall off the Throat of the World). How it works, as already stated, is that he can put his target under a genjutsu without them realizing it’s a genjutsu, or that anything is wrong at all. And he can recharge it faster than anyone else could possibly hope to do. Now to add something. What it works ON is the target’s memories, shifting and altering them at Shisui’s whim in order to make people behave in new and different ways.
Naruto can talk-no-jutsu people. Shisui can AUTHOR-no jutsu people. He can essentially rewrite who someone is under his genjutsu (but he doesn’t, because he’s a nice guy, and because all of the subtlety would be lost once someone close to the target is like “wait, you’re acting completely out of character, wtf is going on?”). So like I said, this genjutsu is past op, it’s just straight up broken.
Itachi, on the other hand, we’ve seen use more genjutsu skills than Shisui (mostly because Shisui is dead and doesn’t get much screen time). His Tsukiyomi is basically a death sentence (in his created world, anyway) and he controls time and space within it. It’s pretty powerful, definitely op, but not broken. On the other hand, he can also cast genjutsu with…his other hand. Sorry, couldn’t resist. But he can place someone under a genjutsu with a single finger.
What we should take into account is that this is a fairly recent development. Itachi wasn’t born knowing genjutsu, no one is (except maybe that girl in the fillers back in the original series). We get to see Itachi’s incredible genjutsu skills because…Shisui is dead. Fifteen-year-old Itachi wasn’t that good with genjutsu. I mean, he was awesome, but he wasn’t as awesome with it as he gets later. Experience and all that.
So, comparatively speaking, had Shisui lived past the age of 15/16, we probably would have seen a great deal more of his genjutsu skills, which he also would have honed in the ANBU, and likely seen skills that surpassed even Itachi’s (who looked UP to Shisui as a mentor/big brother figure). This is speculation, of course, since we’re talking about a character who DIED when Itachi was only 13 years old. Being dead is kind of an important factor.
(Also, usage of Izanami and Izanagi don’t count since you just need a Sharingan to use them, so Shisui had access as well)
So, sheer power to the point of the ability being broken definitely goes to Shisui. Versatility…might go to Itachi, but we can’t say for sure, since we don’t know the extent of Shisui’s arsenal of genjutsu (Kishi need to give us a list of that one of these days). But, based purely on the facts that he had such a powerful genjutsu at his disposal, he was part of the ANBU, and a genius prodigy lauded by the entire clan even before Itachi, who also unlocked his Mangekyo Sharingan YEARS before Itachi did, I’m going to take a shot in the dark and say that had Shisui lived, Itachi would not have become the pinnacle of genjutsu users that he eventually became. Itachi’s status at the top likely hinges on Shisui’s death.
Honestly, I think that Itachi would gladly trade that status and his MS just to have his best friend back. But as both of them have passed on, we’ll probably never know for sure which of them was the greatest genjutsu user in the history of the Uchiha clan. Because let’s face it, for a clan that supposedly specializes in genjutsu, most of their top tier fighters don’t seem to use it much, and those that do are beasts with it (and Madara doesn’t count, since he needed massive power-ups, a bunch of demons, and abilities that weren’t even his own to cast the Infinite Tsukiyomi, and then he relied on a fruit tree to do it for him)
This was originally posted on Quora and was posted via the syndicate network