Chibaku Tensei (episode)

is episode 167 of the Naruto: Shippuden anime.

Synopsis
After Hinata is taken down by Pain, Naruto becomes enraged, which causes the release of the Nine Tails' chakra. He then changes into his four-tailed form and attacks Pain. He progresses in his transformation to a six-tailed form and bombards Pain in a flurry of enhanced attacks. Pain retreats in order to perform Chibaku Tensei. The technique rips apart the ground creating a small moon and traps Naruto inside of it. On a mission elsewhere, Yamato senses Naruto has broken the seal and aborts his mission to track Kabuto, to return to Konohagakure. At this time, Naruto, who was already in his eight-tailed form, trying to escape, after being captured in Chibaku Tensei, is within his sub-conscience reflecting on conflicting feelings of pain and anguish, he succumbs to the Nine Tails' will, but as he was about to release the seal on the Nine Tails containment, the Fourth Hokage, appears to stop him.

Trivia

 * This episode's animation quality created a polemic discussion, whether the studios did well or bad. The animation of Pain's movements and face lost quality and the usual seriousness. Some say it was an entire episode made by an entirely different studio.