1(Black Clover)

An Au where Asta has always been a girl but everyone except Yuno and the people from their village were oblivious to this until certain point.

How did no one from the Black Bulls notice Asta is a girl? She always takes a bath on times no one else does and she washes her own clothes besides due to her having such noticeable muscles most people assume her chest is bigger due to her training and not to her being biologically a woman?

Why doesn't Asta correct them when they refer to her as a boy? She was always closer to boys and treated as one of them besides she never cared about how people referred to her(as if she did, then she would have given up on her dream).

And how would everyone find out she is a woman? It mostly would depend on the writer but maybe during a training with most squads someone accidentally cuts her shirt but before her shirt falls, Yuno is covering her chest with his jacket/shirt and telling her that she should use more resistant clothes at it isn't well seen for a girl to show her chest, or maybe one day as the Black Bulls encounter members from other squads Asta(who is a very happy person) seems in a terrible mood and Yuno simply buys her a few sweets and asks if she needs anything else to help with her period, or even have someone from Hange see Asta and treat her by 'she/her' and then the Black Bulls ask her why she didn't correct the person and Asta goes 'Correct them? About what? I'm woman so it makes sense for them to refer to me as such...'

Basically it is up to the writers imagination and they can use any ships they wish.