Uzumaki ( http://shannaro.wordpress.com/2010/04/08/naruto-chapter-490-whats-behind-door-number-six/ ) said that Minato, the fourth hokage and any of the other hokages before Tsunade can't be summoned because of the "DEMON REAPER SEAL JUTSU" which seals the user and its targets into the demon for eternity. However, this information is bad because in Orochimaru's battle against Hiruzen Sarutobi, the 3rd Hokage, the coffin that could not be activated was that of the 4th Hokage.
It is definitely somebody or something that is strong enough to oppose Madara Uchiha.
It could be one of the following:
1/ The 4th Hokage who was a formidable adversary for Madara.
2/ Izuna Uchiha who was said to be as gifted as Madara.
3/ The sage of the six paths is another strong option. Several indications as to the existence of the sage have been given, including the tailed beasts which date back to the times of the sage and the rinnegan, which can read the secret tablet of the Uchiha.
It can't be Madara himself though. Madara was recognised by Itachi and the Kyuubi.
Uzumaki ( http://shannaro.wordpress.com/2010/04/08/naruto-chapter-490-whats-behind-door-number-six/ ) said that Minato, the fourth hokage and any of the other hokages before Tsunade can't be summoned because of the "DEMON REAPER SEAL JUTSU" which seals the user and its targets into the demon for eternity. However, this information is bad because in Orochimaru's battle against Hiruzen Sarutobi, the 3rd Hokage, the coffin that could not be activated was that of the 4th Hokage.
It is definitely somebody or something that is strong enough to oppose Madara Uchiha.
It could be one of the following:
1/ The 4th Hokage who was a formidable adversary for Madara.
2/ Izuna Uchiha who was said to be as gifted as Madara.
3/ The sage of the six paths is another strong option. Several indications as to the existence of the sage have been given, including the tailed beasts which date back to the times of the sage and the rinnegan, which can read the secret tablet of the Uchiha.
It can't be Madara himself though. Madara was recognised by Itachi and the Kyuubi.
it's Naruto's father,the fourth.