The Buccaneer race of One Piece might be one of the most unexplored aspects, given how the race was only focused on a singular time. However, the mysteries related to them might be groundbreaking, and the biggest one could be the crime they committed, due to which the race was reduced to slavery. Surprisingly, this crime might be the invention of the series' power-scaling.
The Buccaneer race is known for its extraordinary willpower, and this willpower could have led to the first member of this race awakening his Haki powers. Moreover, they might also be able to share this 'Haki' with others. This might also be the 'sin' this race committed against the World, due to which they were reduced to slavery (hoping to lower their willpower).
Disclaimer: This article contains potential spoilers from the manga series and expresses the author's opinion.
One Piece: Exploring the true sin of the Buccaneer race

The Buccaneer race is one of the few near-extinction races from One Piece. The members of this race resemble giants and have very strong bodies. The race was formally introduced during Kuma's flashback in the Egghead Arc, where it was also revealed that this clan has an indestructible willpower.
The most famous members of this race include the former warlord and the father of Jewelry Bonney, Bartholomew Kuma. This character is also the last survivor of this near-extinct race. While the powers of this race are still unknown, some speculate that their strong body structure might be their ace during battle. However, the true strength of this race might lie in the sin they committed.

As revealed during Kuma's flashback in One Piece, this race committed a sin against the World Government, due to which they were reduced to slavery. Ironically, their sin might lie in their indomitable willpower, which might be the true pioneer of Haki (the physical manifestation of a person's spiritual energy).
With devil fruits already creating things hard for the World Government, Haki might have introduced new issues. Moreover, as teased during Kuma's flashback in One Piece, the race could also pass their willpower to others, meaning that the Buccaneer clan might have invented Haki and later passed it onto the other world.
This might be the 'sin' this race committed against the World Government, and the Monarch forced them into slavery, hoping to suppress their extraordinary willpower. This might be how the race soon went extinct because it was impossible to suppress their willpower, leading to World Government officials killing the members of this race.
Read Also: One Piece's Buccaneer race ties directly into the series' biggest theme
Analysis and final thoughts
The concept of linking 'willpowers' with 'Haki' is quite interesting, given how only a few characters possess this ability. This would also increase the lore around Haki, being the second power-scaling of One Piece after the devil fruit powers, and make it stand out as a power-up enough to dominate the Grand Line.
Related Links
- One-Piece fans already know what the Buccaneers' crime is and this theory proves it
- One Piece chapter 1095: What is Kuma's true race, and how it connects to Joy Boy? Explained
- One-Piece's Mariejois straw hat can still be Joy Boy's, and may tease him as a Buccaneer