Living Corpse Reincarnation

This jutsu, developed by Orochimaru, allows him to transfer his mind to someone else's body. If repeated periodically, it basically grants the user immortality as long as they can find new host bodies and keep the host alive. Orochimaru can only perform this technique once every three years. It also seems that when the three years are almost over, he is forced to move into another host, as the previous one begins to reject him. Presumably, if he had a proper container, he could stay in the host for a full lifetime. The fact that he wants to prepare Sasuke Uchiha for the transfer before performing it seems to reinforce this.
 * Name:
 * Type: Kinjutsu, S-rank, Supplementary
 * User: Orochimaru
 * Debut (Anime): Naruto Episode
 * Debut (Manga): Chapter 199

To perform this technique, Orochimaru reveals his true form, a gigantic white snake composed of smaller white snakes, by abandoning his current host's body. Orochimaru then swallows the new host and takes him or her to a different dimension, where he envelops the mind of his victim. The snake body then dies, and Orochimaru's soul dominates the body (though the Sharingan seems to be able to negate and reverse the process against Orochimaru). The souls of the hosts are kept alive within Orochimaru, leaving them "still alive," in a sense (albeit suppressed), and when Orochimaru switches hosts, the souls leave with him. Apparently if the host of these souls chakra level falls enough it is possible for them to resurface in material form as seen with Orochimaru surfacing with his own body after Sasuke used up most of his chakra.

Known host candidates

 * Anko Mitarashi (for surviving the application of the cursed seal; rejected due to lost interest in)
 * Itachi Uchiha (for the Sharingan; failed due to Orochimaru being unable to defeat him)
 * Unknown female (for replacing the hand Itachi Uchiha severed; left body after arms being disabled)
 * Kimimaro (for the Shikotsumyaku; rejected due to terminal disease)
 * Kabuto Yakushi (a desperate temporary replacement body before Sasuke Uchiha; given as an offer, but refused)
 * Gen'yumaru (a desperate temporary replacement body before Sasuke Uchiha; left body for Sasuke Uchiha)
 * Guren (for the Crystal Release; rejected due to being too late, possible future candidate, anime only)
 * Sasuke Uchiha (for the Sharingan; failed due to being overpowered, then sealed away)