One Piece

One Piece is set on the Blue Planet, populated by humans and other races such as dwarves (more akin to fairies in size), giants (which also includes the ancient giants and the occasional artificial giants), merfolk, fish-men, long-limbed tribes, long-necked people known as the Snakeneck Tribe, and animal people known as "Minks", as well as the assorted hybrids of different races and artificial races. The Blue Planet is governed by an authoritarian intercontinental organization known as the World Government, consisting of dozens of member countries. The Navy is the military branch of the World Government that protects the known seas from pirates and other criminals. Cipher Pol acts as the World Government's secret police.

While pirates are major opponents of the Government, the ones who directly challenge their rule are the Revolutionary Army who seek to overthrow them. The central tension of the series pits the World Government and their forces, such as the Marines, against pirates.

Eiichiro Oda's interest in pirates began in his childhood, watching the animated series Vicky the Viking, which made him want to draw a manga series revolving around pirates. The reading of pirate biographies influenced Oda to incorporate the characteristics of real-life pirates into many of the characters of One Piece; for example, the character Marshall D. Teach is based on and named after the historical pirate Edward "Blackbeard" Teach. Apart from the history of piracy, Oda's biggest influence is Akira Toriyama and his series Dragon Ball, which is one of his favorite manga.

While working as an assistant to Nobuhiro Watsuki, Oda began writing One Piece in 1996. It started as two one-shot stories entitled Romance Dawn—which would later be used as the title for One Piece's first chapter and volume. They both featured the character of Luffy and included elements that would appear later in the main series. The first of these short stories was published in August 1996 in Shueisha's Akamaru Jump, and reprinted in 2002 in the One Piece Red guidebook.

One Piece is the best-selling manga series in history; in 2012, Oricon, a Japanese company that began its own annual manga sales ranking chart in 2008, reported that the series was the first to sell 100 million copies (the company does not report on sales figures before April 2008). The series had over 300 million copies in circulation by November 2013; over 440 million copies in circulation worldwide by May 2018; 460 million copies by December 2019; 470 million copies by April 2020; and 480 million copies in circulation in forty-three countries worldwide by February 2021. It reached 490 million copies in print worldwide by July 2021. 566 million copies in circulation worldwide.

By March 2026, it had over 600 million copies in circulation worldwide. By 2004, the brand's merchandise had made more than $1 billion in retail sales in Japan.