"Naruto's Ninja Handbook" (爆発!これぞナルト忍法帖～～っ!!, Bakuhatsu! Korezo Naruto Ninpōchō~~!!) is episode 78 of the original Naruto anime.
Naruto attacks Gaara using his shadow clones and performs the One Thousand Years of Death with a kunai and explosive tag, damaging Gaara's form. Sasuke tells Naruto to save Sakura, and that he would hold Gaara off long enough for them to escape. Realising that Gaara is just like him and remembering his conversation with Haku, Naruto produces nine hundred and ninety-nine shadow clones, which all attack Gaara at once. Gaara responds by fully transforming and attempting to crush Naruto, but he escapes by summoning Gamabunta. The toad identifies Gaara's form as Shukaku of the Sand, and agrees to fight alongside Naruto after learning that he protected his son, quickly severing Shukaku's right arm. Emerging from Shukaku's head, Gaara uses the Feigning Sleep Technique and falls asleep, handing over control to Shukaku and drastically increasing its power. Realising they stand no chance unless they wake Gaara up, Gamabunta tries to grab hold of Shukaku. After the initial attempt fails, Gamabunta tells Naruto to use the Combination Transformation to transform them into something that has fangs and claws. Charging toward Shukaku, Naruto manages to transform them just in time, becoming the Nine-Tailed Demon Fox.