Living Corpse Reincarnation

The Living Corpse Reincarnation is a technique that was developed by Orochimaru that allows him to transfer his soul to someone else's body.

If periodically repeated, it grants the user immortality as long as they can find new host bodies and keep them 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 weaken and reject him. Presumably, if he had a proper container, he could stay in the host for a full lifetime. The fact that he wanted to prepare Sasuke Uchiha as well as several others for the transfer before performing it seems to reinforce this.

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 separate, mental plane where he envelops the mind of his victim. The snake body then dies and falls apart, 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.

After taking over another body, Orochimaru modifies it to suit his theme of snakes, in order to increase his survival capabilities, such as stretching and bending his body, reconnecting any severed parts, and shedding his skin to heal injuries. This ensures that if Orochimaru cannot transfer body within the three years' time, he can allow it to greatly heal and evade attacks, rendering him virtually immortal; Sasuke refers this as the. Orochimaru also alters the face of his host body to look like his original form.

Known Host Candidates

 * 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).
 * Gen'yūmaru (a desperate temporary replacement body before Sasuke Uchiha; left body for Sasuke Uchiha).
 * Guren (for the Crystal Release; rejected due to being too late, anime only).
 * Sasuke Uchiha (for the Sharingan; failed due to being overpowered, then sealed away).