Okay, quick preface, I don't really like SAO like at all, but I just discovered your account and you've peaked my interest as a trans woman who watched the first season years ago as an egg. What themes did I miss? What makes Kirito trans? I am genuinely curious and want to know because I completely missed that interpretation of the story. I wasn't invested in the story at all, but now you got me curious.
I think it’s most apparent in how she acts in the Phantom Bullet arc. She’s in a feminine avatar and instead of trying to appear more masculine, she plays into it. It first it’s because she’s worried Sinon won’t trust her as a man, but even after Sinon knows, she still keeps up the feminine mannerisms around others.
That’s kinda the jumping off point because after that you can go back and forwards in the timeline and see the change when viewing her through the lens of a closeted trans woman.
In Aincrad she’s prone to isolating herself and putting up this image of an arrogant loner when at every turn she tries to help those around her and is instead very self deprecating.
In Alicization/War of Underworld we see her quite literally lose her grasp on her self image, she has become disconnected from the person she’s recognized as.
Outside of the anime, you also have multiple renders of her in her GGO avi wearing dresses and skirts and looking incredibly happy. In the novels there are multiple lines where she expresses a disconnect from who she is online and who she is in real life.
It’s hard to express all at once but basically once you start looking you’ll never stop finding things that support her transness