I think that the last coffin is sage of the six paths himself...but i'm not sure
but still the person in the coffin must be really something to make madara say
this "kabuto you mad man" and also madaras reaction tells a lot and also how
onoki and other kages and villages and countrys reaction is when they hear madara is involved ...telling clearly what level of ninja madara is and what he is capable...and even onoki said hes literally a moster , even yamato said that
when it comes down to madara he could belive almoust anything....also in the
summit when the kages talked about madara one of them wondered if madara
could be immortal danzo stated perhaps ...even itachi said about madara that
he's immortal and who ever is in that coffin must be really something to put
even madara on edge and wary and on toes....and the only one i can think of
is sage of the six paths that can challenge madara.
