Ancient Weapons in the One Piece World

Ancient Weapons in the One Piece World

Three Ancient Weapons

Although I’ve only recently finished the Whole Cake Island Arc of the One Piece anime, I am up to date on the events of the manga. So, this article is going to include spoilers up to the latest chapter (1040). You’ve been warned.

Now, it looks like we’re going to have the second ancient weapon of the series revealed fairly soon in the manga. And before that happens, I wanted to explain some of my theories surrounding these weapons.

But first, what is an ancient weapon?

An ancient weapon is a weapon created by, or originating from, the ancient civilization that was destroyed during the Void Century. There are three such weapons, named Poseidon, Pluton, and Uranus (Uranos?).

These weapons are said to be the most powerful things on the planet, capable of destroying everything. And because of that, the World Government is very interested in them. They don’t want these weapons to fall into the hands of pirates and they also want to use them for themselves.


Poseidon is the only current ancient weapon we know we’ve seen in the story so far. There are no theories to be had about this one. The true nature of the weapon Poseidon is that it’s a mermaid princess with the ability to talk to and control the Sea Kings.

There’s not always a mermaid princess alive with this ability, but there currently is: Shirahoshi. It’s also implied that the world government, or at least Im, knows that Shirahoshi is the ancient weapon Poseidon.

Even with this knowledge, it’s unclear exactly what they could do to Shirahoshi. Ideally, they’d like to take her power. But I don’t think that’s possible. At best, they could threaten or torture her to force her to control the Sea Kings on their behalf.

Alternatively, they could simply kill her so that she can’t use the Sea Kings against them.

Sea Kings at Fishman Island from the anime series One Piece
Sea Kings at Fishman Island

What’s important about Shirahoshi being Poseidon, though, is that it serves as the basis for my other theories. Ever since we learned the true nature of Poseidon at Fishman Island, I’ve thought that the other two ancient weapons would probably be similar.

Poseidon isn’t a physical weapon. It’s a person, or rather an ability that a person has that allows them to do or control something. In my mind, the same would then be true for Pluton and Uranus, despite there seemingly being evidence to the contrary in prior arcs.

I’ll also say now that it’s possible Joy Boy was the original user of all three ancient weapons. We know he has a connection to Fishman Island because of the Noah, which was created to be pulled by Sea Kings.

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Pluton is the first ancient weapon we heard about way back in Alabasta. It’s also the ancient weapon I believe is going to be revealed soon in the manga. This is probably the most interesting ancient weapon currently because we know a lot about it, but not exactly what it is.

So, what do we know about Pluton?

First, we know that Robin actually knows Pluton’s whereabouts. She’s known this ever since Alabasta. Second, we know that Pluton is a warship of some kind; there were even blueprints for it before Franky burned them.

This may seem obvious at this point in the manga, but ever since the Zou Arc when Momonosuke spoke to Zunesha, I’ve thought their connection would turn out to be what we know as Pluton. I even mentioned this briefly in my Zou review.

Zunesha destroying Jack's ship from the anime series One Piece: Zou
Zunesha destroying Jack’s ship

Momonosuke can talk to and control Zunesha just as Shirahoshi can talk to and control the Sea Kings. Both of them use the Voice of All Things to achieve this. And while Zunesha isn’t a literal battleship, it functions as one. It roams the seas, has people living on it, and can attack at Momonosuke’s order.

We know that the Minks who live on Zunesha are allied with Wano. Also, we know Zunesha is connected to Wano in some other way. And in the latest manga chapter, it was even revealed that Zunesha was Joy Boy’s “companion.”

Now, “companion” doesn’t really mean ship. But wouldn’t the Straw Hats consider the Going Merry and the Thousand Sunny their companions?

Also, while there were blueprints of Pluton, implying it really is a ship, that doesn’t stop Zunesha from being Pluton. Zunesha could be a ship that was given a mythical Zoan Devil Fruit and forced to wander the seas as a punishment for being so destructive as a battleship.

That would line up with the themes of Water 7 in which the World Government tried to argue that objects themselves could be “evil.”


Uranus is the final ancient weapon we know nothing about. Because it’s named after the Greek god of the sky, most people assume it can fly. Some people have even suggested that it’s Eneru’s ship the Maxim or that it’s the Moon itself. I don’t agree with those two theories, though.

It probably won’t surprise you at this point to learn that I believe Uranus is someone with the ability to talk to and control a living creature. What is that creature? I think it’s whatever hatched from the giant egg we’ve seen on Roger’s ship the Oro Jackson.

And, specifically, I’m going to assume it’s a dragon. Many have theorized that the Celestial Dragons are thus named because they once had dragons. The egg on Roger’s ship is probably the last of those dragons and I’m guessing he stole it from the Celestial Dragons.

A giant egg on Roger's Oro Jackson ship from the anime series One Piece
A giant egg on Roger’s Oro Jackson ship

Now, if that dragon is one part of Uranus, who’s the person who can control it? I think the most natural answer is Vivi. The royal family of Fishman Island possesses Poseidon, the Kozuki Clan of Wano seems to possess Pluton, and so I’m guessing the Nefertari family of Alabasta “possesses” Uranus.

They don’t physically possess it currently. But I’m guessing they were meant to be the protectors of it and Vivi is the one with the power of Uranus. That would explain why Im has taken an interest in Vivi.

Aside from Vivi, my next best guess is Dragon (Luffy’s dad). He has the name and can seemingly control the wind — probably via a Devil Fruit. But aside from that, and having the Will of D, I don’t think he really fits.


Let me know in the comments if you have different theories regarding the ancient weapons. I’m pretty confident in my theories for Pluton and Uranus, though. Pluton seems almost guaranteed at this point, and there’s a lot of evidence for Uranus as well, I think.

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