Quick Answer
The 3 Ancient Weapons (古代兵器, Kodai Heiki) are three weapons capable of destroying the world in One Piece. They were created over 800 years ago, during the Void Century, and their existence is one of the best-kept secrets in the world. The three are: Pluton (a warship, blueprints kept at Wano then destroyed by Franky), Poseidon (the mermaid princess Shirahoshi, who can command the Sea Kings), and Uranus (the most mysterious weapon, possibly controlled by Im-sama from Mary Geoise). Possessing all three would grant the power to destroy or reshape the world.
Article written by the Wanted Store team — sources: One Piece manga vols. 1–110+ by Eiichiro Oda, Toei Animation anime, official SBS. Chapters 357+, 645+, 906+, 1060+. Updated on April 26, 2026.
What Are the Ancient Weapons?
The Ancient Weapons are three weapons of mass destruction forged 800 to 900 years ago, during the war of the Void Century. According to the Poneglyphs (notably the one in Alabasta read by Robin), each weapon possesses enough power to destroy the entire world. The World Government considers them the ultimate threat and has spent 8 centuries preventing their reconstruction or awakening.
They are named after ancient deities:
- Pluton — Roman god of the Underworld (a warship)
- Poseidon — Greek god of the sea (a mermaid princess)
- Uranus — primordial Greek god of the sky (the most mysterious)
1. Pluton — The Ultimate Warship
Characteristics
Pluton is a warship capable of firing cannons powerful enough that a single volley can destroy an entire island. It was built at Water Seven centuries ago by the ancestors of the local shipwrights.
Location and Control
The construction blueprints for Pluton were passed down from generation to generation by the shipwrights of Water Seven. Tom (the master shipwright) entrusted them to Iceburg, who in turn entrusted them to Franky. Franky ultimately destroyed them at Enies Lobby to prevent them from falling into the wrong hands.
The actual ship Pluton is believed to still exist, hidden beneath Wano under Onigashima. It is mentioned by Kaido, though its exact location has not been explicitly confirmed post-Onigashima.
2026 Status
Blueprints destroyed; ship presumed to exist at Wano (uncertain status post-Onigashima). It is the only Ancient Weapon that does not appear to be under anyone’s specific control.
2. Poseidon — The Mermaid Princess
Identity
Poseidon is not an object but a person: Princess Shirahoshi, the mermaid princess of Fish-Man Island. This was revealed by Neptune (her father) to Luffy. Princess Shirahoshi was born with the ability to communicate with and command the Sea Kings.
Powers
Princess Shirahoshi can:
- Summon the Sea Kings (giant, invincible marine creatures)
- Issue them precise commands through mental communication
- Submerge any island by ordering the Sea Kings to sink it
The previous Poseidon (800 years ago) had allied with Joy Boy. Joy Boy’s broken promise to Poseidon is carved onto the Apology Poneglyph found on Fish-Man Island.
2026 Status
Alive on Fish-Man Island, under the protection of Jinbei (former Shichibukai, now a Straw Hat) and Luffy himself, who met and protected her during the Fish-Man Island arc. Her power has never been used at full capacity.
3. Uranus — The Most Mysterious
Canonical Status
Uranus is the least documented Ancient Weapon in the canon. For 1,000+ chapters, it was mentioned only by name (engraved on the Alabasta Poneglyph). The Egghead arc brought strong hints.
Leading Theory Post-Egghead
The attack that destroyed Lulusia Kingdom (chapter 1060) originated from Mary Geoise, from Im-sama‘s throne. The nature of that attack (lasers descending from the sky, ability to raze an entire kingdom) corresponds to the idea of a celestial weapon. This fuels the dominant theory:
Im-sama is the bearer or controller of Uranus, the Ancient Weapon of the Sky.
This theory has become dominant in the community post-Egghead. If confirmed, it would make Im the holder of at least one Ancient Weapon, explaining their immense power.
Joy Boy’s Goal: Reunite the 3 Weapons?
Several theories suggest that Joy Boy’s goal was to reunite the 3 Ancient Weapons in order to either:
- Destroy the Alliance of 20 Kingdoms (the future World Government) that enslaved peoples
- Rebuild the world on more egalitarian foundations
- Permanently liberate the oppressed peoples (Fish-Men, giants, slaves)
If Luffy is the reincarnation of Joy Boy, his quest logically converges on the Ancient Weapons. He already has the friendship of Poseidon (Princess Shirahoshi) and liberated Wano (the theoretical location of Pluton). All that would remain is Uranus — and therefore Im-sama.
Summary Table
| Weapon | Type | Power | Holder (2026) |
|---|---|---|---|
| Pluton | Warship | Destroy an island per volley | Hidden at Wano (uncertain) |
| Poseidon | Mermaid princess (Princess Shirahoshi) | Command the Sea Kings | Fish-Man Island |
| Uranus | Unknown (celestial?) | Destroy at massive range | Im-sama (dominant theory) |
Why Does the World Government Fear the Ancient Weapons?
Three fundamental reasons:
- Destructive power — each weapon can, alone, raze a continent. United, they can destroy or reshape the world.
- Connection to Joy Boy — their awakening would signal the return of the Government’s historical enemy.
- Symbol of equality — the Ancient Weapons are linked to oppressed peoples (merfolk for Poseidon, Water Seven shipwrights for Pluton). Their recovery by the oppressed would be a revolutionary act.
The Government hunts Poneglyph researchers (such as Robin) precisely because they could locate and awaken these weapons.
FAQ — The Ancient Weapons
What are the Ancient Weapons in One Piece?
Three weapons created 800 to 900 years ago during the Void Century, each capable of destroying the world. They are called Pluton, Poseidon and Uranus.
What is Pluton?
A warship capable of destroying an entire island with a single cannon volley. Built at Water Seven centuries ago. Blueprints destroyed by Franky at Enies Lobby. The ship itself is believed to be hidden at Wano.
What is Poseidon?
The mermaid princess Shirahoshi, who can command the Sea Kings. She lives on Fish-Man Island under the protection of Luffy and Jinbei. Her previous incarnation, 800 years ago, was the ally of Joy Boy.
What is Uranus?
The most mysterious Ancient Weapon. Dominant theory post-Egghead: Im-sama is its bearer or controller. The attack that destroyed Lulusia Kingdom from Mary Geoise corresponds to a celestial weapon descending from the sky.
How many Ancient Weapons are there?
Three: Pluton, Poseidon and Uranus. No other weapon in this category has been mentioned in the canon.
Who wants to reunite the Ancient Weapons?
Most likely Luffy as the reincarnation of Joy Boy. He already has the friendship of Poseidon (Princess Shirahoshi) and liberated Wano (the theoretical location of Pluton). He is expected to face Uranus / Im-sama in the final arcs.
Why does the World Government fear the Ancient Weapons?
Because they can destroy or reshape the world, and because their awakening would signal the return of Joy Boy, the Government’s historical enemy. Controlling the Poneglyphs is essential to prevent them from being found.
