Here are the reasons that izuna had somehow possessed obito's body http://www.narutobase.net/manga/Naruto/399/4
Izuna was hurt talking about himself cause the memories were to much and he was clenching himself http://www.narutobase.net/manga/Naruto/597/12
Notice he says only after the fight if it really was obito he would have said he had it all along being his eye which means that izuna possessed him on that day
-Then their is the stuff he has done and knows
-Izuna would hate the leaf for it being senju ruled and what happened to his brother
-Izuna would know all of this stuff about the ms and ems as he was the second person to awaken it in history so he must have awakened obito's in another way after he possessed him
-Tobi and madara are working with each other so it would make sense that tobi is izuna as that would be the only person he trusted with such a thing
-It is possible that izuna was revived in some form as madara had the rinnegan and when he was revived expected nagato to revive him which means you could be revived long after you died.
Of course their are holes like why he was in obito's body or if he was revived prior what body did he have and it is possible that madara lived until the third shinobi world war and used the rinnegan to put izuna's soul in obito's body.
The first collection of scans is useless as we know it is obito's body. Just because they use the same type of comparison does not mean they are the same person. Izuna knew they knew obito but said that showing his face to guy is meaningless as he is bad with faces. And The grave thing could have been a reference to madara making excuses at his own grave.
There is a reason it was shown in a way where you would not think much of it. It is a big hint.
That is possible but obito gave his eyes willingly he has nothing to hurt about.
Almost fell for that fake interview/leak that was going around about this topic.
Due to lack of reasons I see no reason why Izuna is possessing Obito. However there might be something here.
FA showed the scans of Tobi's "I'm Obito!" hints, saying things that only Kakashi and Obito could know about. The same thing he did when talking to Sasuke about his(?) past, giving personal details that only Madara and Izuna could know about.
It would also explain why Izuna, who equaled Madara before the eye transfer, wasn't summoned with Edo Tensei. Kimimaro and Itachi are no longer sick, Itachi and Nagato are no longer disabled (blind and crippled) and have their eyes back in their sockets. Izuna should have been brought back with his eyes intact.
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