Momiji - rabbit - Sohma
He's a girl, but before the end, Hari, Shiggy and Aya, Ren and Kureno (I think) are the only ones who know, she decided to be a guy because of her hate for women....stupid, I know!
That's not true. She was raised as a man because her mother was jealous of her and refused to give birth to her if she wasn't raised male.
