Criteria For Tobi’s Identity
1) He is from the time of Hashirama Senju, and needs to be someone the Kyuubi would instantly recognize.
He is instantly recognized by the Kyuubi, who as far as we know has been sealed away in an Uzumaki jinchuuriki ever since the battle at the Valley of the End, where Uzumaki Mito sealed it into herself. There are no reports of the Kyuubi having broken free aside from in Yondaime’s time. This means that Tobi is someone the Kyuubi met during the time of Hashirama.
Given the way in which he speaks of past events, he has first-hand knowledge of and was emotionally investment in the Uchiha/Senju conflict.
Izuna fits: Uchiha Izuna was from this time period, and for obvious reasons, was personally and emotionally invested in fighting the Senju.
2) He has to have a credible reason for being pissed off at the Uchiha’s making peace with the Senju, and needs to be personally, emotionally invested in Uchiha Izuna’s eyes being given to Uchiha Madara.
“What kind of monster would hurt his beloved younger brother?! All I ever wanted was to protect the Uchiha clan! […] My younger brother accepted his role and willingly gave his eyes to me….[Tobi clenches his arms in anger]. What happened to the hatred we had for them?! What did my brother sacrifice his eyes for?!”
Izuna fits: He has ample reason to be pissed off at the Uchiha, even more so than Uchiha Madara; he sacrificed his eyes and possibly his life to give Madara the EMS in order to protect the Uchiha in their fight against the Senju, only to have them go and make peace? Why did he sacrifice his eyes and his life for them, then?!
3) He has a credible reason for claiming that the eyes Nagato had “were [his] to begin with.”
Izuna fits: If we accept the likelihood that Nagato’s eyes used to be Uchiha Madara’s (who is the only person we know which awakened the Rinnegan), then we also accept that Nagato’s eyes originally belonged to Uchiha Izuna’s, as we know that Uchiha Madara’s EMS eyes originally belonged to Izuna. Izuna fits this perfectly; no one else has a better credible reason to claim Nagato’s eyes “were his to begin with” than Izuna.
4) He needs to be a person whom Uchiha Madara will trust with his own life and rebirth.
Madara trusted Tobi to bring him back to life with Nagato’s powers. This is a major deal. Who would the great Uchiha Madara trust with his own life?
If we accept Madara’s statement that he awakened the Rinnegan shortly before his death, then this also means that he had only a very short period of time to transplant the Rinnegan into child Nagato. This means that he was 100%, utterly dependent on Tobi to carry out the ‘plan’ he mentioned to Kabuto, which included his resurrection.
Madara also gave Tobi access to the Hashirama-related power which he had nearly died for; an incredible show of trust.
Izuna fits: He is Uchiha Madara’s younger brother, and brotherly ties are a major focal point of this manga. We know that Rinnei Tensei can bring the dead back to life, and we know that Uchiha Madara gained the Rinnegan before dying. It would make sense if he used the Rinnegan to bring back Izuna.
Counter-Argument: Nagato wasn’t able to bring back Jiraiya because he had died too long ago! How could Madara bring back Izuna, who had died even longer ago!
Response: Uchiha Madara planned to use Nagato to bring himself back to life. If we accept that Madara died while Nagato was a child (which is necessary, as Nagato was given the Rinnegan as a child), and that Nagato was expected to ‘grow’ into his power, then this shows Madara thought it was fully possible for Nagato to resurrect him, despite years having passed. Which indicates that it is also fully possible for Madara to resurrect Izuna, despite years having passed.
5) He needs to have a credible grudge against Konoha, and has to have waited a long time for his vengeance against Konoha.
Spoken to Kushina: “Do you have any idea how long I’ve waited for this moment?!”
Izuna fits: His reason for a grudge against Konoha are obvious and profound; he gave his eyes to fight against the Senju who controlled the village, then eventually expelled his brother out from it. If we accept that he died or was maimed back in Hashirama’s days, then he has been waiting a long, long time indeed for his vengeance.
6) Tobi needs to be an Uchiha.
Although not Madara, Tobi still needs to have an Uchiha’s body; he uses the sharingan with expertise not seen outside a native Uchiha, and does not appear to have any problems with his body not being suited for the sharingan.
Izuna fits: Self-explanatory.
7) Tobi has to have a credible reason for being at least partly made out of Zetsu goo, even as far back as the fight with Yondaime.
Izuna somewhat fits: Tobi claims that Uchiha Izuna died in battle after losing his eyes. Knowing that Rinnei Tensi is capable of bringing the dead back, and also knowing that Zetsu goo is based off of Hashirama’s DNA, it’s credible that for Madara to bring Izuna back, he had to use Zetsu goo for whatever reason. Admittedly, more data is required here.
8) He has an old, wrinkly face, despite being partially made out of Zetsu goo.
Izuna fits: If we accept that Izuna was brought back to life with the Rinnegan while Nagato was a child, then at least 30+ years have passed, as we know that Nagato (being Jiraiya’s first disciple) should be as old or older than Minato. If Izuna was brought back in a partially ‘real’ body which aged, and if he had died in his 20’s, then he would now be in his 50’s or 60’s, explaining the wrinkly face. This is also supported by the fact that he indicates if Itachi knew some of his secrets, the Amaterasu would have killed him, indicating that at least part of him was non-Zetsu goo and thus vulnerable to being killed.
