⚠️ Spoiler Warning: This article contains spoilers up to the latest chapters of the One Piece manga, including Egghead Arc revelations.
The Straw Hat Is One of One Piece’s Biggest Unsolved Mysteries
Luffy’s straw hat isn’t just a cool accessory — it’s one of the most carefully tracked objects in the entire series. Roger wore it. Shanks inherited it. Luffy treasures it like his life depends on it. And then there’s the giant, frozen straw hat sitting in Mariejois that Im-sama appears to be guarding personally.
Japanese fan theorists have been digging deep, and they’ve compiled six fascinating theories about what the straw hat really means — from ancient weapons to Devil Fruits to Joy Boy’s Haki. Let’s break them all down.
Who Has Worn the Straw Hat? A Complete Timeline
- 800+ years ago: Joy Boy (heavily implied)
- 52+ years ago: Gol D. Roger
- 30 years ago: Shanks (confirmed in flashback, Vol. 95 Ch. 964)
- 12 years ago – present: Monkey D. Luffy
Luffy has also temporarily lent the hat to Nami, Nico Robin, Sweetpea, and Otama — but those are brief moments. The core lineage runs Roger → Shanks → Luffy, and very likely traces back to Joy Boy himself. Luffy calls it his “treasure,” and given how many secrets were hidden inside the Gum-Gum Fruit, it would be strange if the hat were just… a hat.
And don’t forget: a massive, cryogenically preserved straw hat exists in Mariejois (Vol. 90, Ch. 906). Im-sama appears to be watching over it deliberately. That’s not nothing.
Theory 1: The Giant Mariejois Straw Hat Is the Ancient Weapon Uranus
In Chapter 1060, the kingdom of Lulusia was obliterated by something — either Im-sama’s personal ability or the Ancient Weapon Uranus. Assuming it’s Uranus, two questions immediately arise:
- Why did the World Government desperately want Pluton’s blueprints if they already had Uranus?
- Why hadn’t Uranus been used before?
The answer this theory proposes: they couldn’t activate it without the right person. Each Ancient Weapon appears to be tied to a specific royal bloodline:
- Poseidon → Shirahoshi (Ryugu Kingdom)
- Pluton → Kozuki Momonosuke (Wano Country)
- Uranus → Nefertari Vivi (Alabasta Kingdom)
This would explain why Im-sama kept Vivi’s photo intact while slashing Luffy’s and Teach’s — and why Vivi is currently missing. Im-sama needs her. The theory also draws on the Sea Kings’ conversation in Chapter 968, where they hint at two kings — Shirahoshi, and “a king born in a distant sea.” That second king? Vivi, born in Alabasta, 18 years ago.
Doflamingo’s cryptic line about Mariejois’ “national treasure” and the Ope Ope no Mi’s ability to perform “personality transplant surgery” also fits — activating Uranus might literally require Vivi’s heart or body. The frozen straw hat could be part of this activation mechanism, preserved for the moment the right conditions align.
Theory 2: Roger and Luffy’s Straw Hat Contains Joy Boy’s Haki
This theory centers on a precedent already established in canon: Enma still carries Oden’s Haki (Vol. 99, Ch. 1003). Kaido himself recognized it mid-battle. If a sword can retain its wielder’s Haki, why not a hat?
If Joy Boy wore the straw hat, and Joy Boy was a Conqueror’s Haki user (almost certain, given that Nika’s awakened form is linked to him), then the hat could carry residual Haki from 800 years ago.
- Roger couldn’t read the ancient poneglyphs, yet somehow understood the world’s secret — was it the hat?
- Roger had the ability to hear the “Voice of All Things,” but the straw hat may have given him direction
- When Roger realized he was “too early,” he passed the hat to Shanks — entrusting Joy Boy’s will to the next era
Intriguingly, in Chapter 1054, Luffy is shown reading something with the straw hat casting a shadow in the shape of a sun. That’s the kind of deliberate visual detail Oda doesn’t include by accident.
Theory 3: The Yeti Cool Brothers Were Made from Joy Boy’s DNA
This is where things get genuinely wild — and surprisingly well-supported.
The Yeti Cool Brothers (Rock and Scotch) from Punk Hazard are listed in their Vivre Cards with some very suspicious details:
- Age: 25 — born the same year Roger reached Laugh Tale
- Height: 4,250 cm — double that of a normal giant, yet completely unlike any known giant species
- Blood type: S-type RH- — an extremely rare type shared by Sanji, Fisher Tiger, and other characters with altered or unusual genetics
S-type RH- appears consistently in: twins/multiples, fish-men, human-fish hybrids, and artificially modified individuals. Rock and Scotch fit none of the known giant categories — not Ancient Giants, not regular giants. Their slender, almost human-like faces don’t match anything in the series.
The theory: Vegapunk created the Yeti Cool Brothers from Joy Boy’s genetic material (bloodline factor), extracted from the frozen straw hat in Mariejois — specifically from the inner brim, where skin cells would have transferred. Vegapunk was summoned to Mariejois by the Five Elders during his MADS era (confirmed in a cover story, Vol. 106, Ch. 1075 cover), which would have given him access.
Why? The World Government wanted a counter to Nika’s awakening — an artificial giant built from Joy Boy’s own DNA, deployed before the real thing returned. The experiment failed, producing two strange beings who don’t quite fit anywhere in the world’s taxonomy.
And crucially: their faces were never fully revealed. Scotch hides behind a gas mask. Rock’s face is partially obscured. If Joy Boy looks like Luffy (as many fans believe, and Oda has teased), showing their faces would spoil a massive reveal.
Theory 4: The Straw Hat and “One Piece” Complete the Ultimate Outfit
Okay, this one is delightfully absurd — but the evidence is surprisingly solid.
What if the treasure at Laugh Tale is literally a dress? A one piece? Paired with a straw hat, that’s the quintessential summer outfit for women — an iconic Japanese fashion combination that’s been popular for 25+ years.
- Doflamingo’s “national treasure of Mariejois” may refer to the straw hat itself
- The treasure at Laugh Tale (“One Piece”) completing the ensemble would be peak Oda comedy
- Luffy’s mother, Rouge, wears a one-piece dress in her only appearance — possibly a visual hint
- Finding the One Piece = bringing dawn to the world. A summer sunrise. Wearing a sundress and a straw hat.
Is it a serious theory? Probably not. But Oda has earned the benefit of the doubt when it comes to hiding jokes inside world-altering lore.
Theory 5: A Sideways Straw Hat Looks Like the Letter “D”
Tilt a straw hat on its side. The brim curves into a “D” shape. Is this intentional? Probably not on its own — but the theory opens up a fascinating discussion about the Will of D’s real-world inspiration.
The leading candidate: the Knights Templar. Of the order’s 23 Grand Masters between 1118 and 1314, 20 carried the prefix “de” or “des” in their names — a French aristocratic particle equivalent to “of” or “from.” The last Grand Master, Jacques de Molay, was burned at the stake under false charges by King Philip IV of France.
The parallels to One Piece are striking:
- The Templars were unjustly destroyed by a powerful monarch — just as the “Great Kingdom” was erased by the 20 allied nations
- The “D” prefix marks descendants of that lost kingdom’s royalty, just as “de” marked Templar nobility
- Templar remnants allegedly became pirates and Freemasons — exactly the dual legacy of the Will of D in the story
Under this reading, Im-sama maps to King Philip IV, the Revolutionary Army maps to the French citizenry, and the final war will mirror the French Revolution. The “D” isn’t an acronym for Dawn or Demon — it’s a surname prefix marking the bloodline of a destroyed civilization.
Theory 6: Luffy’s Straw Hat Has Eaten a Devil Fruit
We know inanimate objects can eat Devil Fruits — Vegapunk developed this technology, and we’ve seen it used on swords, guns, and even a teakettle. So… could the straw hat be a Devil Fruit user?
The timeline is a problem: the “object Devil Fruit” technology is described as a recent development by Vegapunk, while Luffy received the hat 12 years ago. That makes it unlikely for Luffy’s specific hat.
However — if the straw hat originally belonged to Joy Boy, and Joy Boy’s civilization had technology comparable to Egghead (as Shaka implies in Ch. 1065), then an 800-year-old civilization could have performed the same feat centuries before Vegapunk reinvented it.
Possible fruits the hat could have eaten:
- Fune Fune no Mi, Ancient Type, Uranus Model — making the hat itself the weapon
- Kagi Kagi no Mi (Key-Key Fruit) — making it the literal key to unlocking the One Piece
This would explain why Roger couldn’t claim the treasure — the hat needs to be present at Laugh Tale for the real secret to unlock. Shanks never went to Laugh Tale (confirmed — he was with Roger but stayed behind). Only Luffy, with the hat, can complete the circuit.
So What Is the Straw Hat, Really?
After all six theories, the most likely answer is also the most elegant: the straw hat is a straw hat — but one that carries profound symbolic and perhaps biological weight.
- It contains residual Haki from Joy Boy, passed down through generations of revolutionaries
- It carries bloodline factor that can (or already has) been extracted and used
- It is a symbol of the Sun — worn by those who worship Nika, defying the World Government’s long winter
The giant frozen hat in Mariejois isn’t just a trophy. It’s a threat, a tool, and possibly a promise — kept on ice until the day Joy Boy’s heir finally arrives to reclaim it. Luffy has been wearing that promise on his head this entire time, and he doesn’t even know it yet.
When the truth finally comes out, it’s going to hit like Gear Fifth.