The Fourth Hokage (episode)

is episode 168 of the Naruto: Shippuden anime.

Synopsis
Minato appears within Naruto's psyche and reveals that Tobi was the one behind the Nine-Tailed Demon Fox's attack on the village 16 years ago, theorizing that he's just using Pain to achieve his own goals. He re-activates Naruto's seal to suppress the fox's chakra again, and leaves, placing his faith in his son. Naruto confronts Deva Path and manages to find Nagato's whereabouts through his Sage Mode. They fight again and Naruto manages to break through his Shinra Tensei to launch a final Rasengan at Pain, overcoming his 5 second time limit.