Wasn’t the Male Lead a Female?

Read manhwa Wasn’t the Male Lead a Female? / The Heroine Is a Man / I Told You I Was a Man Dressed as a Woman! / I Told You I Was a Man Disguised as a Woman! / I told you to dress up as a mistress! /남장여주라고 했잖아요!
Ainne lived for eight years without even knowing which novel she was trapped in. Then one day, a knight came looking for me and she realised which novel she was in. Actually, this guy is a woman?! The heroine who’s dressing up as a man, taking the place of her brother?! If that’s the case, she’ll become friends with the heroine and live a comfortable life! But she felt that the heroine was acting a little strangely… She didn’t know that the heroine was actually truly a man! She’s already too deep into the friendship, what should she do now? “Do I really look like a woman?”