The Searchers!! (捜索者たち!!, Sōsakusha-Tachi!!) is chapter 153 of the Naruto manga.
The mark on Naruto's hand is meant to give him a focal point for his chakra output, concentrating the Rasengan's strength on one specific point rather than dissipating it over a larger area. This does little to help him. Meanwhile, Orochimaru is in agony from the seal placed on him by the Third Hokage. With Kabuto unable to do anything for him, they decide to go looking for Tsunade. Kabuto tells him that she is in Tanzaku Quarters, which Jiraiya also finds out in the course of his own investigation. In Tanzaku, Tsunade, a gambler with terrible luck, hits a winning streak, which causes her great concern.