"Sir, we have a situation. There is a flying unicorn on the radar." - Chance missed author, it would have been a first.
@KZO This unicorn doesn't have a gender preference, since it is bound to the summoner no matter what. I would guess. It just happens to have been summoned by females summoner pretty much every time now.
@Xaelath Well it is no beast anyway. Just a supernatural being, that happens to have a Unicorn as the main Avatar in this world, and a girl avatar as a second way to interact with the world. So in my book it doesn't count in that way no matter what.