I read in a spoiler about Pa-Toad telling Naruto that his 9-Tails power will "explode" out from him if he exhausts himself is Sage-mode, depending on how much he exerts himself.
IF this is true, then we can look back at Naruto's transformations, and how his seal works.
1. Naruto first exploded with 9-Tails power after Sasuke was injured. He did not break his seal at this point because he recognized his opponent, and stopped fighting all together. Kakashi thought to himself, if the seal broke, and he said no, but it was about to. This means that the seal reflects Naruto's ability to incorporate the 9-Tails chakra into his body, where his own chakra was depleted.
2. Naruto fights Sasuke, and we see the 9-tails Cloak, ie 1-Tail. I think we see this happen because Naruto has developed a "Chakra Reserve." This I think is VERY important. Before the fight, Jiraiya told Naruto that when he runs out of chakra, he is able to use the 9-tails. I think this is proportional to his own chakra.
3. Naruto trains with Jiraiya for a while, comes back, and is able to use 9-Tails up to 3-Tails. We assume Naruto's "Chakra Reserve" has expanded as well.
4. Naruto fights Orochimaru, and we see the 4-Tails pushing the seal beyond Naruto's ability to control it. Naruto chose for this to happen, because of his intense rage. He was immature at this point, and let it happen.
5. Naruto goes through huge training with Kakashi and Pa-Toad which expands his Chakra reserve A LOT!!!
If we continue this trend, it means that Naruto is only able to control the 9-Tails Chakra if it is in his CAPACITY to do so. THUS, if Naruto tries to "infuse" his body with 9-Tails chakra beyond his OWN BODY's chakra capacity, the seal will be opened further, and the 9-Tails chakra will pour out of his body. I wouldn't be surprised to see Naruto able to go to 5-Tails WITHOUT losing control of his own self.
IF this is true, then we can look back at Naruto's transformations, and how his seal works.
1. Naruto first exploded with 9-Tails power after Sasuke was injured. He did not break his seal at this point because he recognized his opponent, and stopped fighting all together. Kakashi thought to himself, if the seal broke, and he said no, but it was about to. This means that the seal reflects Naruto's ability to incorporate the 9-Tails chakra into his body, where his own chakra was depleted.
2. Naruto fights Sasuke, and we see the 9-tails Cloak, ie 1-Tail. I think we see this happen because Naruto has developed a "Chakra Reserve." This I think is VERY important. Before the fight, Jiraiya told Naruto that when he runs out of chakra, he is able to use the 9-tails. I think this is proportional to his own chakra.
3. Naruto trains with Jiraiya for a while, comes back, and is able to use 9-Tails up to 3-Tails. We assume Naruto's "Chakra Reserve" has expanded as well.
4. Naruto fights Orochimaru, and we see the 4-Tails pushing the seal beyond Naruto's ability to control it. Naruto chose for this to happen, because of his intense rage. He was immature at this point, and let it happen.
5. Naruto goes through huge training with Kakashi and Pa-Toad which expands his Chakra reserve A LOT!!!
If we continue this trend, it means that Naruto is only able to control the 9-Tails Chakra if it is in his CAPACITY to do so. THUS, if Naruto tries to "infuse" his body with 9-Tails chakra beyond his OWN BODY's chakra capacity, the seal will be opened further, and the 9-Tails chakra will pour out of his body. I wouldn't be surprised to see Naruto able to go to 5-Tails WITHOUT losing control of his own self.
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