You know, I don’t get it. If you’re embarrassed about someone seeing your naked body, you’re embarrassed about someone seeing your naked body. I don’t understand why it would be different if the other party is the same sex as you or not. It doesn’t suddenly make it any more or less embarrassing, and it’s not like homosexuality is a new concept, so regardless the other party might feel something... sexual from it. It would make more sense to me if she explained why it was okay for the twins using the age gap. Really she shouldn’t even consider family members would have a sexual attraction to seeing her naked. The fact that she does for Haruki means she probably sees him less as a brother and more as a guy close to her age. But seriously I never understood all the over the top reactions girls have to guys accidentally seeing them change in manga, but not to other girls seeing them change. There’s really no difference (and that’s not to say they should be okay with guys seeing them change, but that if their embarrassed in one situation they should be embarrassed in the other).