Hard to believe Maho is putting so much effort into seduction when she hasn't had her first kiss yet. And that's some risque lingerie, especially on pages 4 and 15.
Bro can't even make the difference between brown and pink hair in his memory...
Maybe Akane's hair is more red or auburn than brown, so it's not that far off. Maybe it's like that quintuplets series where all the girls actually have the same hair color, but because of artistic license, their hair looks slightly different so the audience can tell them apart more easily. Maybe pink isn't supposed to be Maho's natural hair color, but the result of hair dye, in which case it makes sense that she wouldn't have the same hair color as in the flashback.
we're supposed to think she actually really kicked them out without clothes, and then they actually accepted it and left, with 2/3 of them knowing there's a medicine issue?
It sounds like Maho's been trying to keep her condition a secret so Akane wouldn't worry, so Akane has no clue about the medicine.