This is one of those topics that truly fascinate me.

The most interesting thing about the Geisha culture and world, is that the very first Geisha (in a formal and strict denomination) were actually men. The reason being that the laws of the Tokugawa shogunate in order to abolish protitution forbid women from engaging into any type of activities that meant to "entertain" men; so they turned into the services of young men who looked a lot like women (One of the consequences of such actions prevails today in Kabuki theatre in which all performers are men). Eventually, these female impersonators engaged in prostitution as much or more than their female precessors resulting in the lift of the ban for women to be able to work on "entertainment".

Soon after, a strict differentiation took place between the Geisha and the actual licensed courtesans. Actual Geisha were strictly forbidden to sell or have sex to protect the reputation of their okiya; this is how they ended up becoming real artists and well-spoken and knowledgeable male companions.

I just find incredibly interesting how this society came to be what it is now from such circumstancial events and how much the influence of the Tokugawa regime changed some of the most iconic symbols of Japan ^__________^

yeah, first ones were men.
You can read a great book about Japan by Keneth Henshall