The Two Students

is episode 169 of the Naruto: Shippuden anime.

Synopsis
As Hinata is being healed by Sakura, Naruto defeats the Deva Path with a Rasengan. Naruto pulls chakra receivers out of the Deva Path and uses them to locate the real Pain. Team Guy, wanting to go to Naruto to assist him, are told by Katsuyu that he doesn't want any back up. As Naruto approaches Nagato and Konan, Nagato launches a rod into Naruto, who simply uses the fox's chakra to disturb that of Pain. Naruto then asks why Nagato and Konan are a part of the Akatsuki, and Nagato ends with telling Naruto that they have to go back into his past.

Trivia

 * In the omake of this episode, Ino and Sakura beg Tsunade to see how she looked in her childhood, upon finding out that she used to change to whatever form of her previous ages she wanted during her travels with Shizune and Tonton. She transforms into her childhood appearance, only to have Sakura and Ino stare intensely at her chest, mildly frightening Tsunade. The two jealous kunoichi then furiously harass their mentor with questions about her lifestyle growing up to see how she got her rather enormous chest; for example, the things that she ate. Overwhelmed and angry, Tsunade transforms back into her usual self and shakes the two off by smashing the ground with her Painful Sky Leg.