In the original story, there was one glaring oversight: Madara Uchiha. All the others summoned were in the state they had been in just before death, but Madara alone was at the peak of his prime. When Madara died, he had been a scrawny old man. Put him beside Chiyo, and they even looked rather like a married couple.
Chiyo, who had been reincarnated as an old woman, refused to accept that.
There was another point: Madara had only awakened the Rinnegan shortly before his death. In other words, Madara at his peak had not possessed the Rinnegan. Yet the Madara reincarnated by Kabuto came with the Rinnegan. Kabuto explained that he had tampered with Madara's body, so could that be understood as him putting the Rinnegan onto Madara?
There was nothing wrong with that explanation.
But the problem was that Nagato, who had also been brought back through Impure World Reincarnation, possessed the Rinnegan too. Yet Nagato's Rinnegan had not been his own—it had been entrusted to him by Madara Uchiha, and was meant to be returned.
Had an extra pair of Rinnegan appeared?
Or had Impure World Reincarnation become so absurdly powerful that it could create Rinnegan?
And why had Jiraiya, Shisui Uchiha, and even Shimura Danzō not been reincarnated?
Jiraiya was easier to explain. Perhaps Orochimaru could not bear to disturb the peace of his good friend's soul, or perhaps Jiraiya had not died and would appear as Kashin Koji or something.
But Shisui was rather baffling. Was there not enough DNA?
Even Kinkaku and Ginkaku, who had perished alongside Tobirama Senju, had been summoned. How old had Orochimaru been back then—a little kid?
At most, he would have been a teenager.
Hayato had once guessed that if there was someone capable of collecting the DNA of