Big Adventure! The Quest for the Fourth Hokage's Legacy Part 2

is episode 171 of the Naruto: Shippūden anime.

Synopsis
Naruto and the others take on the oncoming challenges in order to find the secret technique and break the previous record set by the Fourth Hokage, but Naruto’s impulsive action leads the group into various troubles. While Naruto and his friends search for the Fourth Hokage's Legacy in the temple, the fifteen Amegakure Ninja come up from behind and used Grudge Rain, flooding the temple. Luckily, Sasuke arrived and defeated the Rain Ninjas with his new Chidori.