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Kairoseki Infobox
Japanese Name: 海楼石
Romanized Name: Kairōseki
Official English Name: Sea-Prism Stone
First Appearance: Chapter 100, Episode 53[1]
Translated as: Seastone
Literal meaning: Sea Watchtower Stone

Kairoseki (海楼石 Kairōseki?, translated as "Seastone"; literally meaning "Sea Watchtower Stone"), called Sea-Prism Stone in the English versions, and Cherry Stone in One Piece: Grand Battle, is a naturally occurring (though apparently rare) substance that can drain the energy of Devil Fruit users to the point where they can't consciously control their powers. Dr. Vegapunk has invented revolutionary ways to use this rare substance. The Marines appear to have vast quantities of it, using it for jail cells, handcuffs, weapons, and the bottoms of battleships.


It is stated by Pagaya that Kairoseki contains a compound known as Pyrobloin (パイロブロイン Pairoburoin?) which when separated from Kairoseki can help to create Island Clouds or Sea Clouds. [2]

How it Affects Devil Fruit UsersEdit

It was stated by Vice Admiral Smoker that Seastone "gives off a wavelength that is the same as the sea itself" making him refer to it as a solid form of the sea. So far the material has only shown effect upon actual contact with someone who has eaten a Devil Fruit. Upon contact the material drains the victim's body of energy, and stops them from controlling their Devil Fruit powers - having the same effect as throwing them into the sea.[3]

The degree of "weakness" induced by the Kairoseki depends on its density and composition; for example, Kairoseki handcuffs rob the prisoner of their abilities, but still allow the prisoner to walk around normally. Kairoseki only works upon direct and constant contact, which explains how Smoker can carry a Kairoseki-tipped jitte on his back, without it disabling him (presumably, thick clothing will prevent the Kairoseki's effect from harming the victim).

However, it has been shown that though a Devil Fruit user loses his powers when in contact with the Kairoseki, said powers can still be used on the Kairoseki, as shown seen when Mr. 3's candle wax key could open Kairoseki cuffs and cell doors, though this may be because the locks themselves are not made of Kairoseki or because the wax has no Devil Fruit powers inside it as shown when he unlocked Ace's Kairoseki handcuffs. Another example is when Shiki levitated battleships in Marineford, despite the hulls being lined with Kairoseki. Trafalgar Law was also able to switch Kairoseki chains with regular ones, using his abilities.[4]

Other EffectsEdit

The effects of Kairoseki also affect creatures of the sea such as Sea Kings. By layering the bottom of the ships with Kairoseki, creatures that are underneath the ship will be unaware of the vessel, and thus will not attack it.[5] However, while the Kairoseki hides the movements of the vessel traversing above the Sea Kings, that does not mean they still cannot see the ship.[6] Kairoseki is as hard as diamond.[7] This, along with the effect of Devil Fruits, is researched by Dr. Vegapunk, a Marine scientist.[5]


Typically, Kairoseki is primarily found in the form of restraining devices, such as shackles or cages, but they have other uses. Thus, it is deployed as a Devil Fruit counter by the Marines as well as other groups like the Shichibukai and Cipher Pol. Some devices are adapted so the Marines with Devil Fruits can use these weapons, without actually making contact with the device themselves, an event which would nullify their own powers in the process of trying to handle another with a Devil Fruit ability.


  • Nanashaku Jitte: Smoker's jitte, where the tip is made of Kairoseki, so Smoker can use it to nullify his opponent's Devil Fruit powers.[3]
  • Wiper's Skates: Wiper's skate-type Waver has added Kairoseki, so he could use it to nullify Enel's Logia abilities.
  • Battle Smasher: Zephyr's large mechanical arm is embedded with Kairoseki, allowing him to effectively nullify Devil Fruit powers.
  • Bullets: Zephyr uses them for long-ranged attacks against Devil Fruit users, such as Monkey D. Luffy. Those bullets not only wound Devil Fruit users, but also rob them of their strength and their ability to use their powers until they are extracted, making them very effective weapons.


  • Kairoseki Net: Used in Loguetown, a net made of Kairoseki was thrown on Buggy and Alvida completely preventing them from using their powers.[1] Alternatively, it was used to capture Monkey D. Luffy, Buggy, and Mr. 3 in Impel Down, but the Sphinx tore it apart, indicating that only parts of the net contain Kairoseki, while the rest is steel cable.
  • Kairoseki Cage: Seen in Alabasta, it was used by Crocodile to drain Luffy and Smoker's powers and make them unable to use their Devil Fruit abilities. The Government's central prison, Impel Down, also uses Kairoseki cages.
  • Kairoseki Cuffs: A special handcuff made to arrest those with Devil Fruit powers. The lock is made of Kairoseki so that when a Devil Fruit user is wearing them, they cannot use their powers, but unlike other Kairoseki, it does not inhibit their mobility. During the Enies Lobby raid, Nico Robin wore them until Sogeking delivered the key to the bridge; despite being unable to use her powers to fight back, she was able to move, and could attempt to escape or otherwise resist being taken to the Gates of Justice. Sogeking tried to throw Kairoseki handcuffs at Jabra and Kaku in order to prevent them from using their Devil Fruit powers and make them easier to defeat, but got distracted by Kaku's "square" giraffe face and accidentally threw them on Zoro's wrist, and got handcuffed to him while also ducking due to Kaku's Amanedachi. These were also hooked onto Ace's arms and legs in his prison cell in Impel Down to prevent him from using his Devil Fruit powers. Onigumo also clasped one onto Marco during the war in Marineford, to nullify his Devil Fruit powers.

Other UsesEdit

  • Marine Ships: Dr. Vegapunk has discovered that Kairoseki can mask the presence of a ship from Sea Kings and other sea-dwellers, and therefore had the bottom of Marine ships covered in a layer of it, which is especially useful when traveling across the Calm Belt.[5] However, the Sea Kings can still see the ship, so it is not an absolute protection.[6]
  • Jewelry: Nico Robin was weakened by a jewel (a Sea-Prism Stone necklace) in the filler Episode 142 when she tried to stop Ian from escaping the Rainbow Mist.
  • Fortification: Some people use it to fortify sensitive buildings and facilities, making them virtually indestructible. Donquixote Doflamingo's SMILE Factory is made out of Kairoseki.[8]


  1. 1.0 1.1 One Piece Manga and Anime — Vol. 12 Chapter 100 (p. 8) and Episode 53, Smoker uses Kairoseki Net to capture the Buggy and Alvida Alliance.
  2. One Piece Manga and Anime — Vol. 26 Chapter 240 and Episode 154, Pagaya explains creation of island and sea clouds.
  3. 3.0 3.1 One Piece Manga and Anime — Vol. 19 Chapter 169 (p. 11) and Episode 106, Smoker mentions that all Marine Headquarters' prisons are made of seastone.
  4. One Piece Manga and Anime — Vol. 68 Chapter 677 (p. 10) and Episode 603, Law explains how he has replaced the Kairoseki chain with an ordinary one.
  5. 5.0 5.1 5.2 One Piece Manga and Anime — Vol. 45 Chapter 433 and Episode 315, Kairoseki on ships noted by Coby.
  6. 6.0 6.1 One Piece Manga and Anime — Vol. 53 Chapter 516 and Episode 410, the Kuja pirates spot a dead Sea King and Momonga notes though they can move above the Sea Kings nest unnoticed, it does not hide them from the creatures' sight.
  7. One Piece Manga and Anime — Vol. 42 Chapter 400 (p. 11) and Episode 285, Fukuro tells the Straw Hats about Kairoseki.
  8. One Piece Manga — Vol. 75 Chapter 745 (p. 3), a Donquixote Pirate reveals that the SMILE Factory is made of Kairoseki.

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Former Marines
Canon: Kong   •  Kuzan   •  Jaguar D. Saul   •  Vergo   •  X Drake   •  Morgan   •  Bell-mère   •  Diez Barrels   •  Caesar Clown 
Non-Canon: Zephyr   •  Shuzo   •  Randolph   •  Daddy Masterson   •  Minchey   •  Gasparde   •  Ain   •  Binz 
Ship(s): Marine Ships  •  Alexandra  •  Stan Malay  •  Pine Peak  •  Salamander
Vehicles: Billower Bike  •  Ao Chari
Devil Fruit Based: Moku Moku no Mi  •  Ori Ori no Mi  •  Hie Hie no Mi  •  Beri Beri no Mi  •  Sabi Sabi no Mi  •  Shari Shari no Mi  •  Pika Pika no Mi  •  Magu Magu no Mi  •  Woshu Woshu no Mi  •  Hito Hito no Mi, Model: Daibutsu  •  Gasu Gasu no Mi  •  Nagi Nagi no Mi  •  Ame Ame no Mi   •  Modo Modo no Mi   •  Mosa Mosa no Mi 
Fighting Style Based: Haki  •  Rokushiki
Weapon Based: Shigure  •  Kashu  •  Yamaoroshi  •  Nanashaku Jitte  •  Same-kiri Bocho  •  Buster Call  •  Pacifista  •  Dyna Stone
Related Articles
Marine Bases: Base of Marine Headquarters  •  Marineford  •  G-1  •  G-2  •  G-3  •  G-5  •  G-8  •  8th Branch  •  16th Branch  •  77th Branch  •  80th Branch  •  153rd Branch  •  Hand Island  •  Firs Island
Story Arcs: Romance Dawn Arc  •  Baratie Arc  •  Arlong Park Arc  •  Loguetown Arc  •  Little Garden Arc  •  Alabasta Arc  •  Jaya Arc  •  Long Ring Long Land Arc  •  Water 7 Arc  •  Enies Lobby Arc  •  Post-Enies Lobby Arc  •  Thriller Bark Arc  •  Sabaody Archipelago Arc  •  Amazon Lily Arc  •  Impel Down Arc  •  Marineford Arc  •  Post-War Arc  •  Return to Sabaody Arc  •  Punk Hazard Arc  •  Dressrosa Arc
Mini-Series: Diary of Coby-Meppo  •  Jango's Dance Paradise  •  Wapol's Omnivorous Hurrah  •  Ace's Great Blackbeard Search  •  Miss Goldenweek's "Operation: Meet Baroque Works"  •  CP9's Independent Report  •  Straw Hat's Separation Serial
Other: World Government  •  Marine Ranks (Admiral, Vice Admiral)  •  Justice  •  Bounties  •  Kairoseki  •  Battle of Marineford  •  Ox Bell  •  Ocean Guide
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Enies Lobby
CP9: Spandam (and Funkfreed)  •  Rob Lucci (and Hattori)  •  Kaku  •  Jabra  •  Blueno  •  Kumadori  •  Fukuro  •  Kalifa  •  Nero
Enies Lobby Staff: Baskerville  •  Watchdog Unit of the Law  •  Just Eleven Jurymen  •  Oimo (former)  •  Kashi (former)  •  Gatherine  •  Jorge
Devil Fruit Based: Zo Zo no Mi  •  Neko Neko no Mi, Model: Leopard  •  Ushi Ushi no Mi, Model: Giraffe  •  Inu Inu no Mi, Model: Wolf  •  Doa Doa no Mi  •  Awa Awa no Mi
Fighting Styles Based: Rokushiki  •  Yontoryu  •  Life Return  •  Doriki
Related Articles
Story Arcs: Water 7 Arc  •  Enies Lobby Arc
Mini-Series: CP9's Independent Report
Locations: Calm Belt  •  Water 7  •  Gates of Justice
Other: Sea Train  •  Kairoseki  •  Cipher Pol  •  World Government
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Neo Marines
Members: Zephyr  •  Ain  •  Binz  •  Shuzo
Ships: White Tiger
Devil Fruit based: Modo Modo no Mi  •  Mosa Mosa no Mi
Weapon based: Dyna Stone  •  Battle Smasher  •  Shiro Kuma  •  Alpacacino
Fighting Style based: Haki  •  Rokushiki
Related Articles
Movie and Other media: One Piece Film Z  •  Z's Ambition Arc
Locations: New World  •  Endpoints  •  Firs Island  •  Secon Island  •  Piriodo
Others: Marines (Admiral)  •  Cyborgs  •  Kairoseki  •  Ocean Guide

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