This includes Unzan
When you say gender-swapped Unzan, I hear "girl bulging with rippling muscles and chest-hair". And that makes Ethan Jr. very sad.
Remilia could brag about being THE real Vlad Tepes rather than just his descendant; wouldn't be any more true but I'm sure it'd inflate her ego even further. I wonder how much more it'd take for it to just pop?
More importantly, we'd have...
(couldn't really find the Man-Ran picture I'm using as an avatar in a larger format, but that one too.)
Rinnosuke will become Womannosuke monthly. And it won't be pretty...
Momiji will have to change her name to Dadiji. ...Or not. Wait, a male Momiji? Nooooo....
Miko'd be the proper gender, at least, consider "she"'s actually supposed to be a "he" (either that or Prince Shotaku was one heck of a convincing cross-dresser!). Frankly she makes me wonder if the Hakurei Barrier doesn't lock someone's gender to "female"; not sure how the small handful of males would fit into this though... Anyhow, I digress.
I fear for what Utsuho's "third leg" might turn into...
I'm pretty sure the "Futatsuiwa" bit about Mamizou would've taken an entirely more terrifying form. I shudder to imagine this being used as a spellcard...
Also, Reimu's armpits? Yeah, that little joke will acquire an entirely different meaning... X_x
What if Reimu became a youkai? (Can't help but feel this was asked in some way before... My appologies if it was.)