Chapter 0 is called "Strong World". It is a special chapter released with Chapter 565. It introduces the events 20–25 years before Monkey D. Luffy began his adventure, and the story of Shiki for the 10th One Piece Movie: Strong World.
At Edd War, the Roger Pirates prepare to clash with Shiki and the Golden Lion Pirates. Shiki wants Roger to join him with his knowledge of an ancient weapon, but Roger refuses and eventually escapes the fight when a huge storm wipes out half of Shiki's fleet. Years later, after Roger becomes the King of Pirates, Shiki discovers that he has been captured. Hearing this, he heads to Marineford, is defeated by Garp and Sengoku, and sent to Impel Down. Shiki later manages to escape and begins plotting his revenge on the island of Merveille in the Grand Line. At the same time, many of the events that take place in the current story are beginning, such as the beginning of the Red Hair Pirates and the dawn of the Great Age of Pirates.
In Marineford, Marine Headquarters get word that Gol D. Roger and Gold Lion Shiki are having a confrontation. Hearing this, Vice-Admiral Monkey D. Garp walks out on the current Fleet Admiral, Kong, and forces his way onto Admiral Sengoku's ship, much to Sengoku's annoyance.
In the New World, at someplace in the sea, the Edd War is about to begin, Buggy freaks out at the potential conflict between the infamous pirates, and asks Crocus if Roger is well enough to fight. Crocus 'assures' him that Roger is perfectly okay. Meanwhile, Shiki asks Roger to join him, hoping to use Roger's information on the Ancient Weapons to rule the world. Roger refuses, not wanting to give up the freedom he has. A battle between the two crews ensues, and a change in the weather allows the Roger Pirates to sink half of Shiki's ships. A side-effect of the battle causes half of a steering wheel to become implanted into Shiki's head.
After conquering the Grand Line and becoming the Pirate King, the Roger Pirates mysteriously disbanded. A year later, news gets out that the Marines have arrested Roger. Furious, Shiki attacks Marine Headquarters and is told by Sengoku and Garp that Roger will be executed in Loguetown, East Blue, as a warning to all pirates. Shiki is infuriated even more that the Pirate King will die in the weakest sea, but Garp tells him that East Blue is also the symbol of peace. A battle between the three erupts, and ends with half of Marineford being leveled and Shiki sent to Impel Down.
A week after Shiki's captured, Roger is executed, sparking the Great Age of Pirates. All over the world, people have different reactions to the news...
Logue Town: Buggy and Shanks mourn for the loss of their captain while Gekko Moriah and Donquixote Doflamingo look eager to watch the execution. Dracule Mihawk, and Monkey D. Dragon seem neutral, while Crocodile's reaction is not seen.
In Impel Down, Shiki is able to escape his cell by cutting off his legs, freeing himself from the seastone shackles locked there. As news on his escape makes headlines, Shiki replaces his lost limbs with his swords .
In the East Blue, Garp hears about the escape while visiting baby Ace. At what will someday become Zoro's training dojo in Crescent Moon Village, Koshiro comments on how he hoped his child would take over someday, but his child ended up born a girl, Kuina. On Gecko Island, Shanks asks Yasopp to join his crew. Meanwhile, in Syrup Village, Merry begins designing a ship he will call the Going Merry. At a Marine Base, Bellemere claims that she will kill Shiki if he ever attacks the East Blue. Elsewhere, Zeff hears about the escape. On Drum Island, Dr. Kureha watches as Hililuk botches another examination. Meanwhile, Dalton and the then king of Drum Island discuss Wapol's behavior. In an unnamed town, Nico Robin hides from pursuers. Back in the East Blue, on the Island of Strange Animals, Gaimon gets stuck in his chest. In Water 7, Tom's Workers take a break from the construction of the Sea Train. At Reverse Mountain, Crocus tells Laboon that he could find no sign of the Rumbar Pirates, while Brook continues his lonely antics on his ship. At the Sabaody Archipelago, Hatchan visits Silvers Rayleigh who is reading about Shiki's escape.
On the Moby Dick, Shiki asks Whitebeard if he would like to join him. Whitebeard threatens to kill Shiki if that's all he's here for, to which Shiki says he will lay low for a while, before showing the world what a true pirate is.
On Merveille in the Grand Line, Shiki meets up with his subordinate Dr. Indigo, who has discovered a land of strange, monstrous creatures. Indigo says that the plan will take twenty years to prepare, to which Shiki decides that in twenty years he will show the world what hell is...