Chakra is not needed to open a seal what? Contradicting yourself I seeYou're applying the same rules of breaking genjutsu to reopening tenketsu. I'm not twisting your words but that is what you're doing. The manga showed us external chakra stored in a different place can reopen tenketsu. Tenketsu is how people generate chakra it doesn't take away their ability to possess it or use it which the manga already showed.
If that's true Naruto would have needed chakra to activate the seal from kurama regardless of th chakra mixing because he was out of stamina. If Sakura was creating the seal on spot then I would agree but I don't imagine the seal needing chakra to be released.
But anyways like I said the manga showed Kurama's chakra was need not his own chakra, you can make whatever theory you like but its a DIFFERENT chakra being used that is not only stronger but can willingly give chakra unlike the Yin Seal
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