Gol D. Roger was known as the Pirate King, the strongest and most infamous being to have sailed the Grand Line. The capture and death of Roger by the World Government brought a change throughout the world. His last words before his death revealed the location 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 most coveted of titles for the person who found it, the title of the Pirate King. Enter Monkey D. Luffy, a 17-year-old boy that defies your standard definition of a pirate. Rather than the popular persona of a wicked, hardened, toothless pirate who ransacks villages for fun, Luffy’s reason for being a pirate is one of pure wonder; the thought of an exciting adventure and meeting new and intriguing people, along with finding One Piece, are his reasons of becoming a pirate. 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 One Piece.

Stories of old tell of four otherworldly heroes—wielding the sword, spear, bow, and shield—who defended the land from wave after wave of calamity. With the fate of the world in balance, the kingdom of Melromarc summons these legendary figures; in modern-day Japan, the call is answered, and the unwitting heroes are transported to this fantasy universe. Thrust into Melromarc and given the title of "Shield Hero," otaku Naofumi Iwatani is labeled the weakest due to his lack of offensive capability and apparent inexperience. When the heroes part ways to start their journeys, he only has one willing companion: the beautiful princess Malty Melromarc. However, she soon betrays him, steals all his money, and accuses him of taking advantage of her. For his alleged crimes, Naofumi is branded a criminal and made outcast of society. With hatred filling his heart, he sets out alone, vowing vengeance against those who wronged him.