There have been many characters who were believed to be dead during ONE PIECE, but most of these have returned in ways that are sometimes rational while other times in an extremely forced way. Also in ONE PIECE 1008 there was such a moment.
As Luffy and Kaido fight on the top of Onigashima, below them are tens of thousands of people who are doing everything to make their faction win. The protagonists of ONE PIECE are clashing with the officers of the pirates of the Hundred Beasts, but there is also another faction that is moving in the shadows, that of the Kurozumi. The Orochi clan seemed to have been annihilated after the latest events, and instead the shogun has come back to life. After the beheading on the main stage, many wondered if Orochi was really dead.
In chapter 1008 of ONE PIECE Eiichiro Oda confirmed that Orochi is still alive and well and indeed he is taking revenge against Kaido by setting fire to all of Onigashima. The emperor’s palace is set ablaze room after room as the shogun unleashes his anger and the accompanying Fukurojuku is killing everyone who saw the scene.
How did Orochi get back to life? The chances are either that the beheaded Orochi on stage was a clone created by Kanjuro who smelled a possible betrayal, although it is the least likely hypothesis given that the body does not seem to have disappeared immediately, or Orochi was able to survive thanks to an ability of his Devil Fruit.