The Successor (受け継ぐ者, Uketsugumono) is chapter 171 of the Naruto manga.
Orochimaru falls to the ground. Manda, humiliated, promises to kill Orochimaru the next time they meet before disappearing. Orochimaru regroups with Kabuto and tells Tsunade that, even if she won't heal his arms, he has one other way of regaining the ability to perform techniques. Tsunade and Jiraiya see that his face has been torn away, revealing someone else underneath. He and Kabuto flee. Jiraiya is too injured to follow and Tsunade, having expended all of her chakra, loses her youthful appearance. They take Naruto back to Tanzaku Quarters to rest. When he wakes up he tells Tsunade that she will be a terrible Hokage. Tsunade challenges him to a fight and Naruto is once again out-classed. Rather than defeat him, Tsunade kisses him on the forehead. They head back to Konoha, Tsunade is confident Naruto will someday be a wonderful Hokage.