‘One Piece’ creator Eiichiro Oda hides series’ biggest secret under the ocean as manga hits 600 million copies

The long-running manga One Piece has crossed a major publishing milestone, surpassing 600 million copies in global circulation with the release of Volume 114. To mark the achievement, creator Eiichiro Oda has taken an unusual step to preserve one of the series’ greatest mysteries.

In a special project revealed through an official video, Oda wrote down the answer to the central question of the story — the nature of the legendary treasure known as One Piece — for the first time. The handwritten note also addressed the identity and significance of the series’ protagonist, Monkey D. Luffy.

The page was then split in two. The upper section, which asks, “What is One Piece? And who is Monkey D. Luffy?” has been publicly displayed, while the portion containing the answer was sealed inside a treasure chest. The container was placed within a pressure-resistant glass sphere and lowered roughly 651 meters beneath the ocean’s surface at an undisclosed location.
According to the video, the chest will remain underwater until the manga reaches its conclusion, when the document will be retrieved and the contents revealed.

The underwater deployment was carried out with technical oversight from researchers at the Japan Agency for Marine-Earth Science and Technology along with the Strategic Innovation Promotion Program. The teams supervised the installation and filming process while assessing potential environmental impact on marine ecosystems.

First published in 1997 in Shueisha’s Weekly Shonen Jump, One Piece has grown into one of the most successful manga franchises ever. The series’ circulation has increased by about 90 million copies in the past three years alone.

The milestone also coincides with the launch of a new global character popularity poll, inviting fans worldwide to vote among more than 1,500 characters from the expansive pirate adventure.