Sharingan Lore

20. Kakashi's 'Discovery' of Kamui

I've seen a lot of fans mistakenly assume that Kakashi not using the Mangekyou Sharingan until Part II is a plot hole. But it's not a plot hole at all and makes perfect sense within the story.

Kakashi didn't even know he had the Mangekyou Sharingan until he discovered it much later at some point, nor was there any way for him to know that. Remember, a Sharingan user doesn't necessarily know if their eyes change or upgrade unless they are particularly sensitive and attuned to their eyes, which Kakashi definitely wasn't, considering that he is a non-native user and isn't naturally adapted to the Sharingan like the Uchiha are. That's why Kakashi isn't able to deactivate his Sharingan, something that an Uchiha would be able to do. I don't know how much Kakashi even knew about the Mangekyou Sharingan to begin with. In Part II it's clear that Kakashi still doesn't quite fully understand the abilities of Mangekyou, even though he's literally using it.

When Kakashi first alludes to his ability to use Kamui, he tells Sakura and Naruto that he "created" a new jutsu, even though we know that one doesn't create the Mangekyou Sharingan or its abilities. You awaken those abilities; they aren't created or invented. But we the audience know that because we viewers know the Sharingan rules; Kakashi does not. Kakashi is clearly not well informed about the Mangekyou Sharingan or its abilities or its usage, thus why he mistakenly assumes he invented Kamui and that he is the jutsu's first-ever user. And that's a pretty natural assumption for him to make considering how ill-informed and limited on information he is.

If one figured out how to use a jutsu that they had never known of, heard of, or had seen or used before, then it's a pretty natural response for them to assume that they "created" the jutsu, even if in actuality, unbeknownst to them, that jutsu was invented/used by someone a long time ago. Kakashi doesn't know that Kamui is an awakened Mangekyou Sharingan ability; he thinks it's an ability he invented because he figured out how to use it, even with no prior knowledge of how to use Kamui or even that Kamui existed at all.

Kakashi's first attempts at using Kamui are comically and amusingly clumsy compared to the later mastery of Kamui we see, with Obito using Kamui with nice, tight circles. It makes it clear that Kakashi's attempts at using a loose, unprofessional version of Kamui are very amateurish because Kakashi barely knows what he's doing. Kakashi doesn't really understand how Kamui works because he doesn't really even understand it or how he got the ability.

Kakashi is just shooting in the dark and experimenting. He doesn't really understand that the jutsu he believes he created is actually just an ability he's had all along but hasn't stumbled upon until recently.

Thus, Kakashi doesn't know about his Mangekyou Sharingan or that he'd awakened it until he somehow discovered it during the time skip. If anything, the biggest surprise is that Kakashi ever managed to discover he'd awakened the Mangekyou Sharingan at all, and the real wonder is how he was able to discover that and unlock using that ability, particularly since Kakashi can't even turn off his Sharingan so it's pretty impressive that after several years Kakashi was able to figure out the level of control to switch it between its Mangekyou and regular forms.

Besides, it's not like Kakashi would be the first Sharingan-wielding person to be ignorant of the shift in their vision. Sasuke and Sarada were both oblivious to the first time they'd awakened the Sharingan, and Sasuke likewise didn't realize when he'd gained a third tomoe in his Sharingan either. It's pretty common for a Sharingan user to be oblivious to the upgrades in their eyes. I suspect it's fairly common for an Uchiha to have to have their Sharingan upgrades be brought to their attention by someone else and not even realize themselves that they've awakened or upgraded their Sharingan.

So it's not a plot hole, but quite the opposite: it's really good and detailed writing. Kishimoto factored in the individual limitations of character perspectives and how Kakashi's lack of information and understanding of the Sharingan would impact Kakashi's discovery of a Mangekyou power, even at first mistakenly attributing the newly discovered power as something he created himself instead of attributing it to the Mangekyou Sharingan's abilities. Even the sloppy way Kamui is used speaks to detail in writing; Kakashi isn't an instant master at a jutsu that he doesn't know about. Instead, we are introduced to an unrefined and clumsy version of Kamui when the jutsu is used by someone who doesn't fully comprehend or understand how a Mangekyou Sharingan works or by someone still in the learning stages of using the Kamui ability. It makes total sense that it took Kakashi quite a while to discover such a jutsu, and it makes sense that Kakashi wasn't instantly good at it.