Hello Anon, thank you for asking. I'm okay with non-Prefect OCs, but when the OC is a girl and doesn't disguise her gender, it's different story. This is just my personal preference since NRC is an all-boys school and it was being emphasized in the story. Like when Epel was mistaken for a girl then the others immediately correct him since NRC is an all-boys school.

For Prefect, I can accept Prefect as anything since Prefect is a special case and can be said, anomaly. The comic also proved that Prefect can be a girl.

Again, it's just my personal preference since I'm personally pretty strict and really stick to the canon. Especially for fixed things like NRC being an all-boys school, Prefect is a magicless human, etc. Hence why I created Yuu by taking in-game Prefect's traits and develop her from those traits.

Of course I'm not prohibiting anyone to make non-Prefect female OCs. I just can't find myself comfortable with it even though I tried so hard to get used with it.