The hokages have a crystal ball what are you talking about?For Naruto it's pretty much the mystery of the night that the nine-tails was put into Naruto and what sacrifices took place. If Kushina died that night while giving birth to Naruto and why Minato decided to seal the nine-tails into his own child using a ying-yang method and what he had foreseen. Naruto's future and techniques would be a mystery for anyone since no-one has a crystal ball and change is inevitable. 'That jutsu' could be a secret/mystery but that's up for debate.
Lol oh yes I remember now though that was more like spy-no-vision. One of those plot devices Kishi introduces but we never see again.The hokages have a crystal ball what are you talking about?
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