The Naruto Shinobi Handbook!!

Summary
As Naruto and his thousand shadow clones attack a vulnerable Gaara, all of the onlookers are completely surprised. As a last resort, Gaara completely transforms into Shukaku and tries to crush Naruto with his sand. Still refusing to lose, Naruto uses the Nine-Tails' chakra to summon Gamabunta to escape. Seeing Shukaku, Gamabunta has no interest in fighting, especially since Naruto has yet to earn his trust. Gamakichi, Gamabunta's son, assures his father that Naruto is a good person since he protected him from Gaara. Enraged that anyone would attack a member of his family, Gamabunta agrees to help.