When Time Stands Still

is episode 166 of the original Naruto anime.

Synopsis
A flashback reveals that Sagi, not Toki, died, and that Toki took on her brother's identity to avenge his death. Toki assumes the identity of the Cursed Warrior, and attempts to attack Mōsō, but is subdued by Mōsō's imitation ninjutsu. Mōsō's Watari ninja and Naruto's group join the battle. While his companions fight the Watari ninja, Naruto pursues Mōsō and is caught in a genjutsu. Mōsō reveals himself to be Hōki the migrating ninja, who plans to travel and collect as many techniques as possible. He seemingly kills Chishima and knocks Naruto underwater. Naruto awakens when Sagi's ghost asks him to save Toki from her desire for revenge and defeat Mōsō.