Big Adventure! The Quest for the Fourth Hokage's Legacy Part 1

is episode 170 of the Naruto: Shippūden anime.

Synopsis
The story goes back to right before the start of the final rounds of the Chūnin Exams. As Naruto trains in preparation for his upcoming match, he hears Jiraiya speak of "the Fourth Hokage’s legacy".

Trivia

 * A poster of Naruto Shippūden 4: The Lost Tower appears in this episode.