The Ancient Weapons Explained: Pluton, Poseidon & Uranus
Three weapons powerful enough to destroy the world, left over from the Void Century. Here's what's confirmed about Pluton, Poseidon and Uranus — and what's still a mystery.
Some of this is confirmed and some is still open; we keep the two apart as we go.
The Ancient Weapons are three world-ending powers that survived from the Void Century. The World Government's fear of them shapes much of the plot — whoever controls all three could, in theory, dictate terms to the entire world.
Poseidon — already revealed
Poseidon isn't a machine; it's a person. The current Mermaid Princess, Shirahoshi, is Poseidon reborn — able to command the giant Sea Kings. This is confirmed, and it ties the weapon directly to Fish-Man Island and Joy Boy's old promise.
Pluton — the ultimate battleship
Pluton is an ancient warship said to be capable of levelling an island in a single shot. Its blueprints were entrusted to Water 7's shipwrights (which is why Franky once held them), and the ship itself is strongly implied to be hidden in Wano.
Uranus — the great unknown
Uranus is the weapon we know least about, and much of what fans say about it is theory rather than fact. Guesses range from a sky/sun-based weapon to something tied to Im and the Empty Throne — but the series hasn't confirmed its nature yet.
Why they matter to the ending
The Ancient Weapons are one of the clearest threads connecting the Void Century to the present. Control of them is a recurring motive for the World Government, Big Mom, Kaido and others — and Poseidon's reveal shows Oda is slowly cashing these in.
FAQ: the Ancient Weapons
What are the three Ancient Weapons? Pluton (a battleship), Poseidon (a person who commands Sea Kings) and Uranus (still unknown).
Who is Poseidon in One Piece? Shirahoshi, the Mermaid Princess of Fish-Man Island.
Where is Pluton? Confirmed to exist with blueprints from Water 7; heavily implied to be hidden in Wano.
