Search for Tsunade Arc

After the failed invasion resulted in the death of the Third Hokage, Jiraiya was tasked with finding a Fifth Hokage. He convinced Naruto to come with him by promising to teach him a new technique that would be stronger than Sasuke's Chidori. Along the way, they were met by Kisame Hoshigaki and Itachi Uchiha, two members of Akatsuki, who sought to capture Naruto for the Nine-Tails sealed within him. Jiraiya was able to draw them off, but Naruto was introduced to the organisation that would become more of a problem for him in Part II. To prepare him for their future encounters, Jiraiya taught him how to use the Rasengan, a technique created by Minato. While Naruto was able to complete the first two steps of the learning process with little difficulty, he struggled to complete the third and thus master the technique.

Naruto and Jiraiya eventually found Tsunade, the ideal candidate for the position of Fifth Hokage. When she turned down the offer, and insulted all those who had previously held the title, an angry Naruto challenged her to a fight and attacked her with an incomplete Rasengan. Although his effort failed to hit her, she was surprised by his progress and made a bet with him: if he could master the technique in a week, she would give him her necklace, but if he couldn't, she would take his money and his frog wallet, Gama-chan. Naruto agreed, and started practising, but in a week's time, he still had yet to finish the training. Disappointed, Tsunade met with Orochimaru, the murderer of the Third Hokage, and Naruto, Jiraiya, and Shizune, Tsunade's assistant, tried to stop her from helping him.

Naruto using the Rasengan for the first time on Kabuto.

Tsunade turned out to have no intention of helping Orochimaru, and fought him and his assistant, Kabuto Yakushi. When Kabuto left her unable to fight, Naruto came to her aid. Although he was getting beaten by Kabuto and Tsunade told him to run, Naruto refused and by using shadow clones to help him form it, Naruto was able to hit Kabuto with a perfected Rasengan, defeating Kabuto and winning the bet. Amazed by his determination to keep to his word and to survive against a superior opponent, Tsunade gave him her necklace, drove off Orochimaru and Kabuto, and accepted the position of Fifth Hokage. They returned to Konoha, Tsunade confidently believing Naruto would someday become a great Hokage.