Oni Oni no Mi, Model: Sea Devil

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Japanese Name:
Japanese Kanji:
English Name:
Meaning: Demon Demon Fruit, Model: Sea Devil
Type: Mythical Zoan
Power: Partial or full transformation into a Sea Devil
Eaten By: Kiri-Nodachi
Creator: 13th Madman


The Oni Oni no Mi, Model: Sea Devil is a Mythical Zoan that allows the user to become a Sea Devil, in the process gaining a number of Devil Fruit realted powers. It was eaten by the Kiri-Nodachi, the sword used by John Jango De Triezieme.


A blackbery with light blue and red swirls.


The user is capable of generating and shaping "Dark Matter" which can affect Devil Fruit in strange ways. It's most useful ability is that in high enough concentrations, the dark matter can even convert water into "Dark Water" that is perfectly harmless to Devil Fruit users (although they may have difficulty swimming through shear lack of practice), but produces Devil Fruit like effects on normal humans (immobility, weakness, and sinking quickly). Dark matter can also be used to hurt Logia users and ignore Devil Fruit powers.

The form of the Sea Devil body itself is similar to a typical devil, but with features such as fins, valves, claws and scales, and some small suckered tentacles like those of an octopus or squid. The half devil and devil forms are composed predominantly (entirely in the case of the full devil) of dark matter, allowing these sections to shapeshift and regenerate. In effect, this allows the user to access just about any physical ability in existence through shapeshifting.


The user can very easily bypass most Devil Fruit related defensive abilities using this fruit, as it can naturally ignore Devil Fruit powers, and has in some cases caused Devil Fruit powers to malfunction catastrophicly. They can also overcome their own biggest weakness, sea water, using dark matter to reverse it's properties. The shapeshifting abilities mean that this fruit can also be used to take on forms similar to other Zoan fruits, or even some Logia abilities, making it very versatile.


The user suffers from standard Devil Fruit weaknesses, provided they are not backed up by sufficient concentrations of dark matter. While dark water has no effect on Devil Fruit users, it will revert very quickly if exposed to ordinary water. If the user directly touches ordinary water at any time, their power will fail. Therefore, they can only enter water that has already been converted entirely, and is not in danger of being turned back. Although transforming the sea is almost entirely impossible, as the shear volume of water in it would cause the dark matter to disintegrate very quickly.


  • As the current "user" of this fruit is a sword, it cannot die in the traditional sense, and it will most likely be many thousands of years before this fruit becomes available again.