"Kabuto Yakushi" (薬師カブト, Yakushi Kabuto) is chapter 584 of the original Naruto manga.
Kabuto was startled by Orochimaru's approach. Orochimaru said he's been watching Kabuto and Nonō for a long time, and invited him to come with him, promising to reveal to him the reason Nonō attacked him and didn't recognise him. Orochimaru then took Kabuto to his medically-equipped hideout, telling Kabuto he's the first person he had brought there. Kabuto questioned Orochimaru on why he brought him there, and Orochimaru was pleased with his enquiring nature. Orochimaru reveals that Root designed for Kabuto and Nonō to kill each other, as they became too skilled as spies, and that their knowledge made them too dangerous. Orochimaru explained that Danzō told Nonō the reason Kabuto joined Root, and she begged him to free Kabuto. Danzō agreed, provided she killed one man, which turned out to be Kabuto, though she wasn't told of this. Orochimaru showed Kabuto photos Nonō was shown through the years, as proof Kabuto was growing up. At some point, the photos were changed, showing someone other than Kabuto, making Nonō believe Kabuto was someone else, living a civilian life, and being sent on missions on different countries, they would never meet. Kabuto figured Orochimaru was sent to kill the one who survived. Orochimaru told him he's correct, and Kabuto attacked him viciously, all the while asking who he is now that the only person who knew him was gone. Orochimaru regurgitates himself, and told Kabuto he's not who he thinks, and that he was like him. He explained to Kabuto that he was the research he made, always changing himself, adding knowledge and skills, and that he valued Kabuto's skill, that being the reason why he assembled that hideout. He added that he planned to create Otogakure, a village without country, and fashioned Kabuto a new background. Kabuto became Orochimaru's spy, pretending to be a spy for Sasori in order to learn about Akatsuki, and aided Orochimaru in his experiments through the years. After Orochimaru's defeat at Sasuke's hand, Kabuto injected himself with blood from Orochimaru's true form's remains, looking for his true self.