from wikipedia: "The title, "Otomen" is a pun made of the Japanese word otome (乙女?), meaning "young lady" or "mistress", and the English word "men". The characters in the series refer to Asuka as an "otomen" and even he himself has done so."
-aside from this very specific Manga reference an "otomen" isn't really even a thing.
The problem with these types of questions is that they bypass the real question of gender definitions. And there seem to be SO many threads concerning things which bypass the issue of gender definitions.