To non-manga readers. Don't answer this question, read if you want, but expect spoilers.The two main theories that I have heard are that it is Madara, and that it is Izuna. I personally believe it is Madara because of two reasons
1) Tobi says that Nagato was suppose to revive him, but Nagato instead used it on the people he killed in Konoha. When Madara gets out of the coffin he thinks he was revived by Nagato.
2) Kabuto says to Madara "your vessel is unique".
Who do you think it is? And why do you think it is that person?
1) Tobi says that Nagato was suppose to revive him, but Nagato instead used it on the people he killed in Konoha. When Madara gets out of the coffin he thinks he was revived by Nagato.
2) Kabuto says to Madara "your vessel is unique".
Who do you think it is? And why do you think it is that person?