Kabuto Yakushi (薬 師カブト) is the personal medic of Orochimaru, assistant, and general right-hand man. As a young boy he was found on a battlefield by a chief medical officer of the Konoha Medical Unit Squad. The officer brought Kabuto with him back to Konoha, raised him as a son, and taught him medical jutsu when he got older. Kabuto went on to spy for many different villages and groups before joining Orochimaru. Kabuto has since used his numerous other affiliations to spy for Orochimaru, such as using his status as a Genin of Konoha to enter the semiannual Chunin Exams and gather information on his fellow participants for Orochimaru's use. Despite his apparent loyalty to Orochimaru, Kabuto's true personality is difficult to discern; he frequently switches from a lighthearted and polite teenager to a twisted and sadistic maniac that enjoys playing mind games with his opponents. While he generally obeys Orochimaru's orders, he is not above healing Orochimaru's enemies or trying to strike up polite conversations with Naruto Uzumaki when they meet. Orochimaru himself seems to have a hard time determining Kabuto's thoughts, and has suggested that Kabuto secretly works against him.
Kabuto is a talented ninja, being compared to Kakashi Hatake in ability on more than one occasion, as well as being shown capable of killing ANBU members with relative ease. The bulk of Kabuto's fighting ability lies in the medical jutsu taught to him by his adoptive father. Through his allegiance to Orochimaru he has also gained many bodies that he can experiment on, allowing him to take his medical abilities to new levels. After Orochimaru's defeat, Kabuto integrates his master's remains into his body as a means to become more powerful and to no longer be the mere tool of others. The remains have since begun trying to take over his body.