The Ones Who Know Everything is chapter 618 of the Naruto manga.
Orochimaru reveals to Taka that they are in front of the ruined Uzumaki Clan's Mask Temple. Here they search for a particular mask, disturbing Suigetsu who found it strange that he knew exactly which one to choose. As they head back towards the village, Sasuke breaks away from the group to survey the village from a high point, which Orochimaru comments as something he needs to do, since Konoha, despite all the hatred Sasuke feels towards the village, is still his birthplace. Arriving at the Uchiha clan's destroyed compound, Sasuke unseals the passageway leading towards the secret room of the Naka Shrine, lamenting the fact somewhat that this was all that was left of the once-great shrine. There, Orochimaru dons the mask which invokes the Shinigami, and explaining as he went along, slashes the Shinigami's stomach releasing the contents. These turn out to be the spirits of those the Shinigami had consumed, which returns Orochimaru's hands to him, but has the negative effect of reflecting the wound on him as well. On Orochimaru's instructions, Jūgo uses natural energy to activate the sporesObito had Zetsu leave on Sasuke to monitor him: six in total. Sacrificing four of them while Jūgo and Suigetsu held down the other two, Orochimaru uses the Summoning: Impure World Reincarnation and then flees to one of the Zetsu's bodies to possess it. As dirt and ash shroud the White Zetsu clones who cry out in anguish the forms of the deceased First, Second, Third, and Fourth Hokage appear before the group — the ones who know everything, having lived through history unfolding during their eras.