User blog comment:DancePowderer/Kong and Sakazuki's Outside Executive Hiring/@comment-3279487-20130704231701

I think maybe they didn't get straight to the admiral position, maybe all the enlisted people went through a trial period as officers, say a year, then Sakazuki&co decided the rankings.



About Ryokugyu, just look at Volume 70 intro image: this guy is Toshiro Mifune a Japanese actor who appeared in almost 170 feature films. He is best known for his 16-film collaboration with filmmaker Akira Kurosawa, from 1948 to 1965, in works such as Rashomon, Seven Samurai, Throne of Blood, and Yojimbo. He also portrayed Musashi Miyamoto in Hiroshi Inagaki's Samurai Trilogy.

But I guess this is just a coincidence.