The Secrete of EDO Tensei
In the chapter Kabuto reveals secrete of the EDO Tensei, which he is using to control all the dead Ninja’s that were brought back to life using EDO Tensei. It looks like Madara hasn’t trusted Kabuto completely as he asks Kabuto that why he has let Onko live and Kabuto says that he needs her to control EDO Tensei as she is familiar to Urochimaro’s powers.
EDO Tensei is a form of Summoning Jutsu. A fixed amount of flesh is required or you can say DNA is required along with one living human sacrifice to perform the ceremony. The souls that are sealed away can not be brought to this impure world from pure world. Just like third Hokage sealed First and Second Hokage’s soul including his own soul using dead demon seal during his battle with Urochimaro. Same goes for Fourth Hokage as his soul was also sealed away with the Kyubi’s soul when Kyubi attacked hidden leaf village back then Fourth Hokage used that same dead demon seal to seal away Kyubi. So the former Hokages can not be brought back to life. Kabuto was unable to get his hands on the body of Jiraya as his body in deep water beyond reach of anyone. The EDO Tensei was originally created by the Second Hokage. But Urochimaro was the one who perfected the EDO Tensei. EDO Tensei is the greatest achievement of Urochimaro. The best thing of EDO Tensei is that it doesn’t have any effect on the user what so ever.
