Gold Roger was known as the "Pirate King," the strongest and most infamous being to have sailed the Grand Line. The capture and execution of Roger by the World Government brought a change throughout the world. His last words before his death revealed the existence of the greatest treasure in the world, One Piece. It was this revelation that brought about the Grand Age of Pirates, men who dreamed of finding One Piece—which promises an unlimited amount of riches and fame—and quite possibly the pinnacle of glory and the title of the Pirate King. Enter Monkey Luffy, a 17-year-old boy who defies your standard definition of a pirate. Rather than the popular persona of a wicked, hardened, toothless pirate ransacking villages for fun, Luffy's reason for being a pirate is one of pure wonder: the thought of an exciting adventure that leads him to intriguing people and ultimately, the promised treasure. Following in the footsteps of his childhood hero, Luffy and his crew travel across the Grand Line, experiencing crazy adventures, unveiling dark mysteries and battling strong enemies, all in order to reach the most coveted of all fortunes—One Piece. [Written by MAL Rewrite]

As dungeon-like treasure vaults started appearing throughout the land, more and more people began signing up as treasure hunters—risking their lives to obtain the vast riches and ancient relics inside. In the imperial capital of Zebrudia, the top hunter party is the Grieving Souls—a group of six childhood friends led by Krai Andrey, who is thought to be the strongest of them due to having a reputed wide array of skills. However, Krai actually has no special talent. His accomplishments are actually the result of his friends being overpowered. Krai has repeatedly attempted to leave the party out of fear his lack of aptitudes would one day cause his companions' downfall. Nevertheless, everyone around Krai thinks differently, making him feel obligated to remain the group's leader.

Nina, thinking it was a lolly, swallows an object called "Crystal Pearl". But the candy turns out to be a test for the magicians. To retrieve the crystal, a special medicine has to be made so now Zero and Ichii, the magicians, have to protect her from others while waiting for the medicine to be completed.