SHE is Kinemon: The Mulan of One Piece
NOTE: This one is just what will possibly happen if the spreading rumors, "th tenth is a girl, confirmed" is true (although not), i know it's ridiculuos but i post it to know your opinions if the first premise comes true.(sorry for the confusion cause i forgot to include this :) )
THEORY:
It's merely a hypothesis but I think Kinemon is a girl in disguise. Momonosuke is probably not his son but a brother. This maybe revealed in the next arc, Wano Country. His/Her story may resemble to Mulan's. Thus, no girls can become samurai. If this is the theme of the story, Zoro may become one of the focus in characters since he may remember Kuina in Kinemon. Aside from that, DonQuixote maybe the main villain in Wano Country (but only 30% probable since …