Arc Length: Chapters 282-310
Team Kakashi is given a new mission to locate whoever is spying for Sasori. Sai joins the team as Sasuke's replacement, which Naruto is not too happy about, and the two of them have difficulty getting along. Due to Kakashi being weakened by the overuse of his Sharingan in the previous arc, he's stuck staying in the hospital and a new man joins Team 7 to replace him: Yamato, a former ANBU operative.
Once they find Sasori's spy, said spy reveals himself as Kabuto. Orochimaru appears and mocks Naruto about Sasuke, provoking Naruto into entering his Superpowered Evil Side state. He ends up injuring Sakura due to his inability to control his wrath, and is only stopped once Yamato uses a special technique on him. Sai, who was secretly following Danzo's orders to meet Orochimaru, betrays Team 7. Orochimaru and Kabuto escape with Sai.
The three of them continue to Orochimaru's lair, where they find Sai - who explains his orders to them - and Kabuto. The animosity between Sai and Naruto ends when Sai pulls a Heel–Face Turn and attacks Kabuto, motivated by Naruto's undying will to save Sasuke. All four succeed in finding Sasuke, but fail in convincing him to return to Konoha. He overwhelms the team with his power and seriously wounds Yamato. The team returns to Konoha, determined not to give up. There, Sai is finally accepted by Naruto and Sakura, and is welcomed as a true member of Team Kakashi.
Tropes:
- Awful Truth: The fact Naruto is responsible for Sakura's injuries sounds like this to him when he realizes it is because of the Nine-Tailed Fox's terrible power.
- Curb-Stomp Battle: Definitely happens between Sasuke and Team 7. Naruto and Sakura didn't even try to fight properly despite two years of training. Naruto at least has the excuse of still healing from going Nine-Tails earlier, with it later being mentioned that even at full health, he wouldn’t have made much headway compared to Sasuke's growth. Sakura, by contrast, only attempts to attack Sasuke once and that doesn’t even get off the ground before Yamato blocks for her, rationalizing that Sasuke is too powerful for her.
- Deadly Upgrade: Naruto's four-tailed mode beats the crap out of Orochimaru, but it also endangers his own life.
- Heel–Face Turn: Sai starts as an unpleasant guy who joined Team 7 only to meet Orochimaru and assassinate Sauske under Danzo's orders, but Naruto's determination to save Sasuke makes him truly become a member of Team 7.
