Here's something that's been bugging me for awhile: the entities sealed within Naruto. I believe that the Yondaime's soul is sealed along with Kyuubi's in Naruto. I speculated that the shiki fujin was a seal that was meant for humans, as demonstrated by Sarutobi and Orochimaru. Therefore, wouldn't it be logical to have to be some kind of reprecussions because of: one, using the seal on a demon, two, using the seal to transfer a soul into another person, and three, sealing a demon's soul within a human's? Also, the Kyuubi admitted there was another presence sealed within Naruto that it couldn't sense? This very entity could be the person who used the seal, the Yondaime himself. And has anyone found it strange that it took Naruto a week to master a technique that took three years for the Yondaime to master? Maybe because his body had past recognition of the technique and therefore took considerably less time to master? Then look at Naruto's uncomparable stamina; couldn't he tap into the Yondaime's chakra much the same way he does the Kyuubi's? However, because of the fact that they are both humans, it would be much less obvious and visible than when he taps into Kyuubi's, who is a demon. This is merely speculation, however, and will remain such until the true identiy of the entity deep within Naruto is revealed.