The Fourth Hokage (四代目火影, Yondaime Hokage) is episode 168 of the Naruto: Shippūden anime.
The Fourth Hokage seems to somehow know Naruto's name, and reveals that he is his father, Minato Namikaze, whose revelation makes Naruto emotional. When Naruto calms down, Minato reveals that a masked man who he believes to be Madara Uchiha was the one behind the Nine-Tails' attack on Konoha sixteen years prior, theorising that he's just using Pain to achieve his own goals. Naruto breaks down in all self-esteem once again, curses and degrades himself, until Minato puts his hand on his head and telling him he believes in his son to find the answer to the question even he or anyone else cannot answer about how to achieve peace. He restores Naruto's seal to suppress the fox's chakra again, and leaves, placing his faith in his son.
Naruto, in Sage Mode once again, confronts Deva Path for the final battle to save Konoha. Pain, aware of the limits of Sage Mode, bargains to beat Naruto half-to-death and haul his body out of there. Meanwhile, Team Guy returns to Konoha and see Hinata unconscious, but still alive. Naruto and Deva Path engage in taijutsu, and Naruto manages to find Nagato's whereabouts through his Sage Mode. Naruto fires a Wind Release: Rasenshuriken but it is repelled, beginning the crucial five-seconds to attack Pain. Debris around the battlefield are revealed to be clones in disguise and attack Pain. After being hit with a powerful Shinra Tensei and withstanding it using his clones, Naruto puts his remaining power into one final Rasengan, effectively hitting the final Pain.