I know, this threat is all ready many years old but I want to reply on this anyway ><
My main UTAU called Aki Toka is Genderfluid. He was originally just "male" but that was mainly because I thought before that UTAU that identifies something else than cisgender must be a "joke" and not serious (*cough* *cough* Vippers) plus I didn't know 4-2 years ago that "non-binary" is actually a REAL thing that exists... Buuut now I know way more than back then and think differently ;D
I have also Azurite the Bird that is intersex, has masculine appearance and likes men <= He's currently only one of my UTAU having a "canon" sexuality
And then Senchou: I still haven't/couldn't decide if Senchou is trans or queer or whatever officially but she likes to be masculine and doesn't like if someone calls they as "she/her". Well, Senchou is Senchou