One Piece is largely considered to be one of the most popular Shonen series of all time. After 22 years, it is still going strong. More importantly, it has left behind plenty of unresolved questions and mysteries, as well as teasers of events that have yet to occur.

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This has led to the creation of plenty of fan theories about certain characters and events. While there are still plenty of theories that are still unconfirmed, some have already been proven true. Some are more recent, while others took quite a few years to be confirmed. Here are 15 One Piece fan theories, that were eventually confirmed to be true.

Last updated: November 29th, 2019 to reflect the latest additions to the wide-world of One Piece fan theories.

15 Buggy Becomes A Shichibukai

Buggy The Clown laughing

Buggy "The Star Clown" was one of the series earliest villains. Overtime, he’s gone from being an antagonist to an unlikely ally of protagonist Monkey D. Luffy. It's later revealed that he is a former underling of the Pirate King Gol D. Roger and former friend of the Yonko "Red-Haired" Shanks. Following the events of the Marineford arc, Buggy receives a message from the World Government. Many fans theorized that the letter was an invitation to join the ranks of the Shichibukai, a group of seven powerful pirates who swear allegiance to the World Government in exchange for a pardon. This theory was eventually confirmed in chapter 700.

14 Momonosuke Is Not Kinemon’s Son

During the Punk Hazard arc, Oda introduced the samurai Kin’emon and his son Momonosuke. However, most fans became convinced they were not truly father and son. This theory was quickly supported by the fanbase based on facts such as the inspiration behind their names, as well as the way that they address each other.

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Some have even pointed out the fact that Kin’emon’s protectiveness of Momonosuke, along with their connection to Kaido, implies there is more to him than just being a regular child. The truth is later revealed in chapter 817 that he is not Kin’mon’s child, but the son of the former Daimyo of Wano, Kozuki Oden.

13 Shirahoshi Is An Ancient Weapon

One Piece - Mermaid Princess Shirahoshi - Poseidon

Among the many theories in One Piece, those about the ancient weapons Pluton, Poseidon and Uranus are especially well known. So far only two of the Ancient Weapons have been revealed, leaving only Uranus shrouded in mystery. Out of the two known weapons, Poseidon is by far the most unique. Unlike the legendary battleship Pluton, Poseidon, which allows one to control sea kings, is a living weapon. Its current form is the mermaid princess Shirahoshi. A few months before this was revealed, one fan theorized that she was an ancient weapon. After opening a poll, most fans voted that that they were wrong. Ironically, their theory was proven correct following the release of chapter 649.

12 Lola’s Mother Is Big Mom

One Piece - Lola - Thriller Bark

Lola, the captain of the Rolling Pirates, first appears during the Thriller Bark arc. She quickly becomes good friends with the Straw Hats and even gives Nami her mother's Vivre Card. At the time, her mother’s identity was still a mystery. A theory was later developed that Lola’s mom was the Yonko Big Mom.

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Before she gives Nami the Vivre Card, she mentions that she was born in the New World. One of her underlings also confirms that her mother was a famous pirate. During the Fishman Island arc, fans noticed that the lips on Big Mom’s Jolly Roger were like Lola’s. This theory was eventually confirmed true in chapter 835.

11 The Sulong Prediction

mink tribe one piece

Members of the Mink Tribe are some of the most powerful fighters in One Piece. Even their children are stronger than most adult pirates. In addition to their superhuman strength and ability to use electrical shocks, minks have the power to transform into a Sulong form. Between the Zou and Whole Cake Island arcs, there were several hints indicating a connection between minks and the full moon. As a result, fans theorized that like the mythical werewolves, minks could transform under a full moon. This was finally confirmed in chapter 888 when Carrot transformed into a Sulong by looking directly at the full moon.

10 Doflamingo’s Devil Fruit Ability

Donquixote Doflamingo wielding the String-String Devil Fruit in One Piece.

Donquixote Doflamingo’s Devil Fruit ability was one of the greatest mysteries in the series. It holds the record for having the longest gap between when it was first used to when it was officially named, which spans over 11 years. The only clues fans had about it was that he could control people, slice off limbs, as well as fly.

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Many fans theorized that his power involved manipulating strings based on how he moves his hands like a puppeteer. There is also the presence of the onomatopoeia "くい" or "kui" – such as in chapter 556 – which is similar to the sound of strings or cords tightening.

9 Kaido Is A Dragon

Kaido Fly

As one of the Yonko, Kaido is one of the strongest characters in the series. In addition to his overwhelming strength, he is seemingly unable to die. Since his introduction, a lot of fans began to speculate that he possessed a powerful Devil Fruit ability. One of the most popular theories was that Kaido is part dragon.

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Evidence that supports this include Kin’emon claiming that he has a vendetta against dragons during the Punk Hazard arc. Another was during the Dressrosa arc, when Momonosuke denies Luffy’s claim that he could fly and addresses it as a terrible thing. This theory was finally confirmed true in chapter 921 when Kaido appears as an eastern dragon flying over Wano using clouds to fly just like Momonosuke.

8 Gear Fourth

gear fourth

During the Enies Lobby arc, Luffy shocked fans by unveiling his new techniques Gear Second and Gear Third. Ever since these techniques were introduced, fans have predicted that he will unlock even more Gear forms. Although it took a few years, this prediction came true with the unveiling of his Gear Fourth transformation in chapter 784.

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There were several theories about what new abilities this form would possess. These include theories like how it would be based on Luffy using his muscles, as well as compressing parts of his body to increase the power and speed of his attacks. Furthermore, fans also predicted that there would be other Gear Fourth forms, which appear during the Whole Cake Island arc.

7 Sabo Is Alive

Sabo In Dressrosa

Following the conclusion of the Marineford arc, fans learn that in addition to Ace, Luffy had another stepbrother named Sabo. Unfortunately, while out at sea Sabo was attacked by a Celestial Dragon and was seemingly killed. Fortunately, Oda leaves plenty of hints in the manga, cover pages and SBS forums supporting a theory that Sabo was still alive.

This includes a moment during a flashback in chapter 589, where the leader of the Revolutionary Army Monkey D. Dragon, returns to his ship carrying an unknown injured person. This led many fans to speculate that the injured person was none other than Sabo. This theory was eventually confirmed as correct during the Dressrosa arc in chapter 731.

6 Sanji’s True Identity

One Piece - Vinsmoke Sanji

One of the best and oldest One Piece theories revolves around the Straw Hats cook Sanji. For many years, there have been different versions of a theory, which claims that Sanji is a prince. Recurring elements of this theory include his “Mr. Prince” alias that he used during the Alabasta arc, his extremely rare blood type, as well as the fact that his wanted poster after the Dressrosa arc stated that he was wanted “only alive”. It was not until chapter 812, that this theory was finally confirmed after Sanji is revealed to be the third son of the Vinsmoke family who rule the Germa Kingdom.

5 Kin'emon Jumped Through Time

Kin'emon mad One Piece

 

When Kin'emon and Momonosuke's true identity was revealed back at Zou, Momonosuke's mention of having met Roger despite being just 8 years old raised quite a few eyebrows in the fandom. Theories started flooding out soon, and some quite rightly predicted that Momonosuke and Kin'emon had jumped through time to the current events of the story, which is how Momonosuke had actually met Gol D. Roger as well.

This was recently confirmed towards the end of Wano Country's Act 1, in Chapter 919 where Kin'emon revealed to Luffy that he, along with some other members of the Red had jumped 20 years ahead into the future.

4 Sanji's Raid Suit

Sanji using The Raid Suit

Towards the end of the Whole Cake Island arc, Vinsmoke Sanji was gifted a Raid Suit by Niji, his brother. Although Sanji exclaimed he would never use it in a fight, it was rather obvious that he would eventually end up doing so. Rather than thinking about whether he would use it or not, fans started thinking about what the abilities of his Raid Suit would be.

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Many arrived at the conclusion that Sanji would gain the powers of invisibility as that's exactly what he wanted right since he was a little kid. In One Piece Chapter 931, Sanji unleashed his new form, O-Soba Mask, where he also showcased the power to turn invisible.

3 Wano Country Is Above The Ocean

When the Strawhat Pirates first entered Wano Country, the Sunny climbed up a couple of waterfalls and then ended up sinking. Although the ship sunk, Luffy ended up on Kuri's beach somehow, and the same was the case with Big Mom, who was thrown into the ocean by King the Wildfire.

Fans predicted that Wano was either inside a mountain, or on top of it with a secret entry from underneath the ocean. As expected, this theory was proven correct in chapter 954 of One Piece, where Kin'emon explained the basic geography of the country.

2 Big Mom Comes To Wano

Charlotte Linlin, also known as Big Mom, in One Piece

One of the biggest predictions that the One Piece fans made prior to the beginning of the Wano Country arc was about Big Mom's eventual intervention in it. With Luffy having dealt serious damage to her reputation, it was easy to predict that she would follow him to the ends of the world.

In One Piece Chapter 907, Big Mom told Kaido that she would eventually come to Wano, which Kaido warned her against. This further strengthened the fans' belief in this theory, and ultimately, Big Mom entered Wano Country in Chapter 930 of One Piece.

1 Whitebeard Was On Rocks Pirates

Whitebeard/Edward Newgate in One Piece.

In the Reverie arc, it was mentioned by Garp that the Rocks Pirates were an incredibly powerful pirate crew that existed 40 years ago. They were said to be rulers of the entire seas and Big Mom and Kaido were hinted to be few of its members. Interestingly, Marco hinted that Whitebeard sailed on a pirate ship about 40 years ago with many other members as well.

As expected, it didn't take the fans long to make a connection and predict that Whitebeard was, in fact, a member of this pirate crew as well. In One Piece Chapter 957, this theory was confirmed when Sengoku explained the history of the Rocks Pirates to us.

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