Four-Tails, the King of Sage Monkeys

is episode 326 of the Naruto: Shippūden anime.

Summary
At the Mountains' Graveyard, Sasuke quickly killed the White Zetsu with his new technique, while removing the bandages around his eyes to reveal his Eternal Mangekyō Sharingan. Elsewhere, Suigetsu and Jūgo discuss Sasuke and Karin while en route to a hideout of Orochimaru. Meanwhile, on the battlefield, Kakashi and Guy battle against the reincarnated jinchūriki. Just as the Five-Tails is about to attack, Tobi releases a chakra chain and subdues the tailed beast. Kakashi speculates that he has to output a lot of chakra to keep them under his control and that when fully transformed, he almost has no control over them. Naruto suddenly hears a voice speaking out for help and the Eight-Tails recognises it as the voice of the Five-Tails. The Eight-Tails also telepathically speaks to Nine-Tails, who shows irritation for humans because they only see the Tailed Beasts as pets they can bend to their will. The fox thinks back to all its previous encounters with Madara, Hashirama, Mito and Kushina. Suddenly Tobi forces Rōshi and Utakata to fully transform, cutting Naruto and B from Kakashi and Guy, ending with the Four-Tails swallowing up Naruto. In an alternate dimension located inside the tailed beast, Naruto meets the beast, who quickly becomes irritated by the former for calling him the Four-Tails and not giving him the respect of using its real name; Son Gokū. After brief discussion about the humans treatment of the tailed beast, upon which Naruto learned the Nine-Tails' name was Kurama, Son comes to realise that Naruto was different than most humans and truly wanted to help it and its kind. Son tells Naruto he could start by removing the chakra chains that bind it, to which Naruto eagerly accepts.