Actually, there are various clues to gender, even in manga. Their legs and waists look very different, with the a female's legs having more slender curves and the waist is often more narrow like an hourglass unlike a male in manga (unless he's created specifically for trap genre or shotacon). The MC was also was wearing heels, her mannerisms were also very female, and the facial characteristics were more female than male, too.
Yeah same. In my long, long, loooooooonnngggg history of reading yaoi I can say that from just looking at the cover I thought she was female. And the more I look at her the more girly she seems.
I just look at her eyes from the cover and i know that she is girl. ╮(￣▽￣)╭
No matter how you look at her, she looks like a guy from the beginning of the chapter to the end. No need to lie...