Board Thread:Boruto Discussions/@comment-33727162-20171121221649/@comment-734582-20171123170128

Vladosaurus wrote: I said that he only has bits as well.He only ever had small bits from the other 8 bijuu. We saw, on screen, without ambiguity, that 6 out of 9 biju gave him chakra. Not a piece of their essence or whatever, plain chakra. We've seen time and again that chakra gifts don't keep. Once used, they are used, they don't regenerate. So we can comfortably say that those 6 biju's gifts are temporary. That leaves Shukaku and Gyuki unaccounted for.

Obito said he tore off a piece of them from Madara, but it was never specified what meant exactly. But we've seen that Gyuki's tails can be cut off yet they regenerate to the main body. So if Obito cut off a piece of Gyuki it's entirely possible that it's just pure chakra. We can extrapolate something similar to Shukaku.

We don't know what exactly Hagoromo did, that made the Biju appear. We've seen that memories can be imprinted into chakra (Minato and Kushina's chakra ghost), and that those memories can act in an autonomous manner and cast jutsu. Actual jutsu, like how Minato restored the seal.

So, it doesn't require any magic. We know given chakra is finite and we know Naruto was given the chakra. We know chakra can act like a Ghost. We don't need to have split biju for this to work, just what Kishimoto already explained earlier in the series.

Besides, the only two people to ever split a biju were Hagoromo (who did the initial) and Minato, who needed the Reaper Death Seal. There's no reason to believe the Biju can split themselves nor is there any reason to believe that Hagoromo can create them from thin air (since he didn't do that the first time).