@MiyamotoMusashi:
I thought i compile and significant piece of information that could be relevant
http://i.imgur.com/xKcSAhJ.jpg
This drawing was included in volume 70 and depicts Mifune Toshiro, probably the most renown Japanese actor. His collaborations with Kurosawa Akira are his most famous movies, including Rashomon, Seven Samurai, Yojimbo The Hidden Fortress and The Bad Sleep Well, except the Samurai Trilogy. Considering that all the Admirals´appearance and, to a certain extent, their personality is based on famous actors in their most popular role, this drawing is somewhat interesting. It is also peculiar that Oda drew Mifune with horns and now introduced a character named Ryokugyuu (Green Bull).
Another interesting fact is that there is a movie in the Zatoichi series called "Zatoichi meets Yojimbo" in which both Shintaro Katsu (Zatoichi) and Mifune (Yojimbo) play side by side. In the movie, Zatoichi is hired by a rich merchant while Yojimbo is hired by the son of said merchant. Considering that Fujitora and Ryokugyuu were both conscripted by the Marines, it could be a parallel, at least somewhat. Furthermore, one of the gang leaders Yojimbo tricks in the 1961 movie is called Ushitora, which consists of ox/bull and tiger.
Considering all that, it is not unlikely that Mifune is really going to be the inspiration for the newest Admiral Ryokugyuu. The thing with Mifune is though that he has way more than one memorable role. I mean, Shintaro Katsu was pretty much Zatoichi, Yusaku Matsuda´s (Aokiji) most remembered role is the detective Shunsaku Kudo in Tantei Monogatari, Bunta Sugawara often played the same type of character that personality-wise resembles Akainu and of course Kunie Tanaka as Borsalino in Truck Yaro.
Mifune on the other hand has so many memorable roles that are sometimes so different. The calculative and smart Ronin Yojimbo Sanjuro, the naive, goofy but lovable, wannabe samurai Kikuchiyo in Seven Samurai, the bandit in Rashomon, the master swordsman Musashi in the Samurai Trilogy and so forth but if that drawing should really be a hint of the Ryokugyuu´s design, it´s probably Yojimbo.
Nice theory Miyamoto. You totally called this awhile back in the Marines thread I think it was.
We always suspected it'd be Shimura or Mifune.