my favorite guesses are izuna (his brother) or someone had a interesting theory on it being kagami (old uchiha teammate of danzo)
PS has never let me down so i do agree with izuna possibly being in the coffin
Has anyone ever thought that Madara had to have a son?
could madara be scared of his son perhaps??
can anyone list what sharigans exsisted and their powers? maybe we could get somewhere if we knew this tidbit of info
Think about their sharigan(ems): each ems power is different with each user madara: time/space
obito(kakashi left eye) time/space
so who is obito's dad???
would obito be a direct decendant of madara?
would itachi/sasuke be a direct decendant of izuna?
izuna was supposed to be a more talented ninja, the same as itachi and sasuke who were both considered genius ninja.
i would have to say that the person in the coffin would have to be an uchiha just for the fact that byokogun(spelling) isnt really comparable to ems and since nagato, well madara has him and his rinnengan.
so many loop holes in all the theories, we dont have enough info and we cant even begin to try and understand kishi's mind/world.
and just to keep on topic: not minato decent try tho