As it stands, majority of oyama_mahiro posts are tagged with genderswap_(mtf). It seems superfluous considering their main appearance in the story is that of a girl.
Looking at other forum topics, I've found a very similar situation in topic #20695. It was resolved by creating separate tags for male and female versions of the character, and I propose to do the same here - either split it into _(male) and _(female), or keep the basic version and add oyama_mahiro_(male) to pre-transformation posts.
What do you think? And which of those alternatives do you prefer?