Admiral Ryokugyu is a big mystery in the community as he hasn’t appeared in the story yet and only received a shadowed figure in Doflamingo’s Throne War speech.
Admiral Color/Elemental Pattern
All the Admirals devil fruit powers and personalities have corresponded to their given alias:
Akainu – Red Dog
Sakazuki’s code name of “Akainu” translates to Red Dog. The color of Red corresponds to his magma powers and the animal motif is his stubborn or loyal personality. The dog part can viewed as he is the World Government’s dog or is rather stubborn in his Absolute Justice belief.
Aokiji – Blue Pheasant
Kuzan’s code name of “Aokiji” translates to Blue Pheasant. The color of Blue corresponds to his ice powers and the animal motif is his free caring and cool personality. Like a bird or pheasant soars through the skies freely.
Kizaru – Yellow Monkey
Bosarlino’s code name of “Kizaru” translates to Yellow Monkey. The color of yellow corresponds to his light powers and the animal motif is his silly personality. Borsarlino like a monkey acts rather silly, even in battle he makes sarcastic remarks and silly faces.
Fujitora – Wisteria Tiger
Issho’s code name of “Fujitora” translates to Wisteria Tiger(or similar shade of Purple). The color of Purple corresponds to his Gravity powers(In fiction the element of Gravity is often portrayed as purple, ex: Final Fantasy) and the animal motif is his royal, calm, but also ferocious personality. Tigers can be calm one moment but ferociously attacking their enemy the next.
I believe Ryokugyu or Green Bull, will most likely follow this pattern.
Ryokugyu‘s Power and Personality
His code name translates to Green Bull. Around the world the color of Green is universally corresponded to Nature for obvious reasons. For this I believe Ryokugyu will have a Devil Fruit that allows him to control or create the element of Nature for combat.
The animal motif of the alias most likely represents a Bull’s stubbornness or selfishness. Moreover, Oda actually hinted at this himself in an SBS:
D: “Could the two new admirals “Ryokugyu” and “Fujitora” possibly have been created with the concept that, despite them being people of the Marines, deep down inside they are both Admirals who secretly harbor ill feelings towards the World Government (going against the WG → kind of like pirates?) as can be seen with Fujitora’s wish to completely abolish the “Shichibukai” system set up by the World Government?” P.N. Tosaka Kouhai
O: “What? Me, becoming restless? (cold sweat) W-w-what are you talking about? Of course not.”
With this I could infer that Ryokugyu actually does not care for the World Government and only took the position of Admiral for themselves be it fame or wealth, since Fujitora took the role of being against the World Government morally.
While doing research for this theory I came across a being in Celtic Mythology that fits the few hints and ideas we have about Ryokugyu(Nature, Bull, and Wealth/Fame/Corrupt): Cernunnos
In Celtic Polytheism, Cernunnos was the horned god of fertility, life, animals, wealth, and the underworld. For these reasons I believe Ryokugyu will have a Mythical Zoan of Cernunnos. Life and Fertility would represent the Nature Element aspect of his power. Furthermore, wealth and the underworld could represent his corrupt personality that focuses on wealth and fame or maybe even dealings in the Black Market. Cernunnos is also the “horned god” and as in the images above has horns like a bull if physicalcharacteristics apply.
*Theory by Law0