why do you see Toya as trans girl
okay. hehehe. long ass post potentially okay.
so firstly just for fun. imo you don't Need a canon basis for headcanons, sometimes it's just for fun and sillay and that's largely what girltoya is for me! i just kinda got attached and find it fun to imagine and think about.
However.
i do also feel really really strongly about how her narrative adapts really well to a queer story and how toya being trans emphasises the themes and enhances her character.
toya's plotline and character development are about growing into oneself. most of toya's events explore aspects of self-expression and understanding; both within the main/event stories and in a lot of side stories, a lot of emphasis is put on toya discovering new experiences he was previously cut off from and learning how to make sense of his own feelings. the way toya moves, speaks, and looks have all changed a lot - reading early-game side stories and comparing them to current ones shows this super well. toya's story is about gaining independence, learning to express previously confusing feelings, and learning who he is.
so it's very easy to reinterpret that into learning who she is.
it's natural that, with all of these new feelings suddenly unravelling as toya learns to be comfortable, something he hadn't even known was there would make itself known. before vivid bad squad, discomfort was toya's normal - he was lonely and hated being at home, his feelings were blurry and impossible to understand, he didn't like himself. that was just how things were. but now, with his own music and friends, those start to fade away, and yet this part - a pervasive and inescapable sense of wrongness with himself and how he exists - stays. once she accepts what it is, manages to decode it and admit to herself and those around her that she wants this, everything suddenly becomes a lot lighter.
if you add transness to toya's story, you can emphasise the preexisting themes of comfort, self-expression, and new experiences and create a much richer version of her character. expressing herself becomes so much easier when she starts to present differently, because she no longer feels unwelcome in her own body. it's easier to talk to people and be part of a group when people aren't constantly perceiving her as something she isn't. all the new things she gets to experience have an extra layer of happiness added, because she's experiencing them as herself. there are additional experiences, too - exploring her style, wearing makeup, learning to navigate the world as a happier, brighter, more comfortable version of herself. by imagining toya as a trans girl, canon moments of self-expression and self-discovery are hugely enhanced. it blends perfectly with the already present story to a degree where you don't even need to change much to make it work.
additionally, i believe that toya being trans makes the theme of rebellion more potent too. toya is rebelling against her father and the "fate" he created for her, by making her own music and finding a place in the world outside of classical, but also by simply being herself. the classical path was pushed on toya primarily by her father, and it is a path her two older brothers followed. by transitioning, toya breaks that cycle - no longer the third prodigial son taught by their father, but rather, a daughter who is fiercely independent and stubborn in the future she found for herself. simply being herself is an act of rebellion. by adding acceptance of toya's girlhood to the plotline of reconciling with harumichi, you can hugely emphasise the love present. he struggles to understand toya and why she would leave a successful future for street music, but he still wants her to be happy. he doesn't fully understand who she is yet, but he's trying.
each of toya's new smiles seems brighter with the addition of transness to her story. it comes with its own complications and troubles, of course but by making toya a trans girl, her happiness seems so much stronger to me - cards and illustrations where toya is smiling brightly always make me instantly flip to she/her pronouns. she's more comfortable now because she has friends and a support system and a more easy to live in home, yes - but also because she's finally living life as the girl she wants to be.
okay so long story short it's something like this: