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 eventually progresses in his transformation to a six-tailed form and bombards Pain in a flurry of enhanced attacks. In the middle of their battle, the First Hokage's Necklace activates and tries to seal away the Nine-Tails' chakra. However, the Nine-Tails is able to over come the sealing process and destroys the necklace before continuing its attack. 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 is generally considered one of the worst in Naruto History due to it's extremely poor animation.