第40話: オロチマルがナルトを挑発し、九尾のチャクラが漏れ出して変身を引き起こす。

40

Yamato signals Naruto, Sakura and Sai to appear on the bridge. On seeing Naruto, Orochimaru begins mocking him and compares him to Sasuke, which causes the Nine-Tails's chakra to leak from an enraged Naruto's body and ascends him to a Three-Tailed form. Meanwhile, Yamato remembers Jiraiya speaking of the appearance of number of tails on Naruto during their training, and had specifically warned of Naruto's Four-Tailed transformation. (Source: Wikipedia) Tenchi Bridge Reconnaissance Mission arc: (8/21)