The Gender Identity of Yamato

In One Piece, Yamato identifies as Kozuki Oden, claiming to be the son of Kaido rather than his daughter, even using male pronouns to refer to himself in Japanese.
Similar to Kikunojo, the gender expression of Yamato is not merely a narrative gimmick but serves to highlight gender fluidity, at least when compared to previous gender expressions in One Piece. Most controversies surrounding Yamato stem from a general misunderstanding and the contrasting perspectives of the fans.
The Functionality of Gear 5 in the Anime

The latest form of Luffy, Gear 5, has received significant backlash since its debut in the anime. Although the manga also faced some skepticism regarding the details, the anime’s introduction of Gear 5 has sparked intense debates due to its overwhelming power.
Many believe that Gear 5 is breaking One Piece and will severely impact future battle dynamics. Others argue that the sheer might of Gear 5 is simply excessive. The Egghead Arc has demonstrated that while Gear 5 can be destructive, it still provides fans with thrilling battles, maintaining the quality and unpredictable nature that One Piece is known for.
Robin’s Skin Tone Change After the Timeskip

Along with the new visuals, One Piece’s timeskip has also altered many members of the Straw Hat crew. One significant change that fans still grapple with is Robin’s lighter skin tone. Alongside Zoro and Usopp, she has undergone a noticeable transformation over time, the reasons for which remain unclear.
Regardless of the reasons, this change continues to be a contentious point even years later, with many fans hoping for Robin to return to her original appearance, which carried symbolic significance for her character.
Fan Service Surrounding Jewelry Bonney

The Egghead Arc of One Piece has prominently featured Jewelry Bonney, despite several recent controversies surrounding her character. Chapter 1098 of One Piece confirms that Bonney is actually only 12 years old, yet she has been depicted utilizing her powers in a rather mature manner.
This detail regarding Bonney’s real age has evoked discomfort among fans, prompting many to feel uneasy. Even the initial part of the Egghead arc depicts Bonney in a rather provocative light, especially during scenes where Blackbeard requests her to transform into his female subordinate.
The Strength of S-Snake’s Ability Over Larger Individuals

Seraphim are among the most formidable new forces introduced in One Piece. In the case of S-Snake, a copy of Boa Hancock, she possesses the same powerful abilities of the Mero Mero no Mi. However, the application of these powers by S-Snake, especially when targeting larger individuals, has led to considerable debate.
The SBS section in Volume 106 of One Piece clarified that the powers of the Mero Mero fruit can still have an effect even when individuals are unaware of its use.
Pell’s “Death”

A decision that sparked controversy and remains etched in the minds of One Piece fans to this day is Pell’s “death.” We witnessed Pell dive into an explosion and then soar into the sky without a scratch while protecting Alabasta. In the anime, viewers were led to believe Pell would perish, but it turned out that he survived without any injury.
This detail is one of the main reasons many fans find it hard to believe that a character actually died when witnessing their corpse or hearing their death mentioned, or sometimes both. More recently, One Piece continues to follow this trend with characters like Igaram, Sabo, and most recently, Vegapunk.
The Disturbing Obsession of Vander Decken with Shirahoshi

In the Fish-Man Island arc, there’s a disturbing obsession that stretches over the years between Vander Decken and Shirahoshi, especially considering that the princess is only 16 while Decken is 25.
Decken does not just pursue Shirahoshi with the powers of his Mero Mero fruit but also attempts to force her into a marriage against her will at a time when she is still very young.
Absalom’s Inappropriate Behavior Towards Nami

In the Thriller Bark arc, Absalom exploited the powers of the Suke Suke no Mi to spy on Nami. His actions towards her could easily be categorized as predatory. He not only violated Nami’s privacy but also attempted to force himself on her, claiming her as his fiancée.
Ultimately, Absalom’s actions are characterized as malicious and aggressive compared to any other behavior depicted in One Piece.
How Kamabakka Queendom Treats Sanji

Despite Bon Clay, Ivankov, and the okama in Impel Down taking on roles as colorful representations of Japanese okama culture, the portrayal of the Kamabakka Queendom during the timeskip does not meet expectations, particularly in regard to the treatment of Sanji.
When Sanji arrives at the Kamabakka Queendom, the okama chase him, trying to transform him into one of their own. This experience is portrayed as a humiliating ordeal for him.
The Jolly Roger of the Whitebeard Pirates

The Jolly Roger of the Whitebeard Pirates is not always the iconic skull and crossbones that fans recognize today. The original symbol of the Whitebeard crew was also Ace’s tattoo, which used to be a simpler design. It changed upon the request of the editorial team to avoid controversies as One Piece began to expand outside of Japan.
Although the symbol is often associated with fortune and good luck, its negative connotations in Western cultures are the main reason it was altered.