wait a second..."I was kinda worried you started hating crossdressing"....emm...does that mean she only dates/hangs out with him because of crossdressing? This is a red flag
the best part is, I am 99% sure if he reveals he is a boy in front of parents especially after they like her version now - nothing will happen, in fact they will be happy no bad boys will touch her daughter
Is this just me or manga artist is making sister's breasts bigger when she have a cozy moment with the MC? Also obviously nipples are getting hard. We saw it in previus chapters as well.
I don't remember reading about her erected nipples in LN.