Sharingan Lore

9. Obito's Posthumous Susano'o

I think Obito's Susano'o veers away from "typical" Sharingan rules, since after all, Obito is granting Kakashi his Mangekyou powers from the afterlife, which makes it an act of the supernatural, not a normal Sharingan ability. Kakashi's/Obito's Susano'o is what I'd call a supernatural phenomenon in the Naruto-verse. One might dub it a miracle, since it goes against the usual rules of the universe, since typically (as far as we are aware) most Uchiha don't get involved in the world's matters after they have died, at least not in the way Obito did, as Obito acted with a kind of godlike power that allowed him to meddle in the world's affairs even after he had died by granting his powers to his best friend.

I'll admit that Obito's Susano'o is a bit of a deux ex machina, but I don't think it breaks the lore of the Sharingan either. It rather expands on the "afterlife" lore of the Naruto-verse. We don't know a whole lot about how the afterlife works in the Naruto-verse, aside from there is a Limbo world and it appears that the deceased can dwell there but also "move on" to the Pure Land (or possibly hell?), as both Rin and Sakumo mention that they can finally move on after their loved one joins them or they find resolution and inner peace that they are looking for, as in Sakumo's case.

The point is that Obito's Sharingan doesn't apply to the normal rules because it's a supernatural act, not a regular one.

A lot of fans seem to assume that Kakashi randomly "awakened" the Mangekyou Sharingan, but that is incorrect. Obito somehow lent his Mangekyou Sharingan to Kakashi, presumably through a kind of spirit possession or something akin to that. Kakashi didn't have the Mangekyou Sharingan; that was Obito's ability that he lent to Kakashi because he couldn't stand to see Kakashi so useless.

Kakashi cannot awaken the Sharingan because he is not an Uchiha and he didn't even have a Sharingan prior to when he received Obito's dual Mangekyou eyes. If Kakashi had awakened the Mangekyou Sharingan during the battle against Kaguya, then it should have been a permanent awakening. But it wasn't; it was a one-time use, and after the battle, Kakashi's eyes went back to normal. I'd say Obito's one-time-use loan to Kakashi is not all that much different from Itachi's granting a one-time use of the Amaterasu to Sasuke. You can't awaken the Mangekyou in another person's eye, but it is possible to loan others the abilities for a one-time use or use for a brief duration.

The extent of Obito's ability to meddle in the world of the living after he died is unclear, because as I said, we don't have a lot of information about the afterlife and how it works in the Naruto-verse or what the rules for it are. The filler established that there are ghosts in the Naruto-verse, and we know an afterlife exists, but we don't know much about the nature of it or how the spiritual realm connects to the physical world of the living.

Thus, I would explain such an unusual phenomenon by saying Obito essentially "loaned" his Mangekyou Sharingan eyes to Kakashi from the afterlife. Obito made it sound as if he was somehow (supernaturally) giving his eyes to Kakashi from his place in the afterlife. So Kakashi was merely borrowing Obito's powers.

Theoretically, once an Uchiha dies, they shouldn't be able to use their powers to change events in the world of the living anymore, but Obito somehow did anyway, and gave his Sharingan powers to Kakashi to use in the fight against Kaguya. So that's why I think it was a supernatural occurrence that falls outside of the realm of usual Sharingan lore; too many things deviate from the typical workings of the Sharingan and even just the rules of Naruto-verse. That, or the Sharingan works differently for a deceased user than a living one, which would lead to a whole other realm of rules about the "afterlife" version of the Sharingan.

After the fight with Kaguya, Kakashi went back to his normal vision. If a non-Uchiha truly awakened the Mangekyou Sharingan power of Susano'o, then even after Kakashi lost his dual MS, he should have retained the ability to use Susano'o. However, that isn't the case, since his Susano'o lasted no longer than his Mangeyou Sharingan, which shows that however Kakashi received Obito's Sharingan, it was not a "true awakening" of the MS in the typical sense, which means that Kakashi's Susano'o isn't typical either.

Since Obito only awakened one Mangekyou eye, and Kakashi only awakened one Mangekyou, neither of them awakened double Mangekyou Sharingan and thus were not able to achieve Susano'o, which is why neither of them use Susano'o until the fight with Kaguya. It's not until Obito's machinations somehow create the "miracle" of causing Kakashi to briefly awaken both Mangekyou Shairngan in his eyes that Kakashi/Obito are capable of using Susano'o thanks to Obito essentially combining his powers with Kakashi.

It's possible that 50% of the ability to use Susano'o was awakened within Kakashi and the other 50% was awakened inside Obito when their Mangekyou Sharingan first awakened, so perhaps when Obito combined his powers with Kakashi's during the Kaguya fight, they were able to create a Susano'o together, a Susano'o that was neither purely Kakashi's nor purely Obito's but both of their Susano'o.

In any case, Obito's Susano'o deviates from the usual Sharingan rules, and even Sasuke notes with incredulity that it's an unusual occurrence. I don't think it breaks the rules of the Naruto-verse itself, but it plays by a different set of rules: the afterlife rules and the rules of the spiritual laws of the Naruto-verse rather than by the typical constraints of Sharingan lore that bind the world of the living. Which is to say, I wouldn't generally consider Obito's Susano'o as a typical example of how the Sharingan rules work, but an exception to the rules.