What story are the two new admirals based off of? Oda-sensei likes to create important characters that are based off real-life people and/or folklore. The three old Admirals are based off characters from tale of Momotaro.

I'm curious to know if there is any in Japanese folklore on the two new Admirals: 
 - Issho (or Isshou) is aka Fujitora (purple tiger)
 - "Green Bull," which Doflamingo talks about in Chapter 713.

I tried googling but I got nothing except for Metamorphic Force.

Does anyone have a clue or something about what animals (and story) these two new admirals are based off of?
Fujitora is clearly based off of Zatoichi.


  Zatoichi at first seems a harmless blind anma (masseur) and bakuto (gambler) who roams around the country, making his living by chō-han (playing dice) as well as giving massages, performing acupuncture and on occasion, singing and playing music; however, secretly, he is also very highly skilled in swordsmanship, specifically Muraku-school kenjutsu and iaido and is equally skilled in the more general sword skills of Japan, as well as Sumo wrestling and kyujutsu


Nothing has been revealed about "Ryokugyu" as of this post.