The Naruto Shinobi Handbook!! (volume)

Synopsis
Sasuke catches up with Gaara, just in time to witness the beginnings of Gaara's transformation. As he begins to assume a monstrous form, Gaara is given enough speed and strength to overcome Sasuke's Chidori. As Gaara is about to finish him off, Naruto arrives to fight save him and fight in his place. After Naruto taps into the power of the demon fox sealed within him, Gaara completes his transformation becoming a life-size replica of Shukaku, the beast sealed within him. To compete with this giant form, Naruto summons the biggest toad he can muster. The toad clashes with Shukaku while Naruto, hoping to end the battle quickly, tries to bring Gaara to his senses.