I'd say she's more dark-skinned than golden, but I guess they sometime call it bronze skin.
What a guy though, tries to go for his sister, ends up getting her tanned friend instead.
That ending though. Well hey, sister, if you want to keep her away from your brother, maybe you should have taken/claimed him for yourself? I mean, I'd certainly have loved to see her get some loving too.
Well, Rei-chan squashed the incestuous urges Natsuhiko had, not that Mao would have given in to them. So, I can't tell if Mao was jealous, overprotective, or if Rei has a casual sex history. Rei is smoking hot regardless - definitively the gal to lose your virginity to.
(In rising and then descending tone) "OOOOOOOOOOOOOOOOOOOOH!"
Quite possibly, Rei-san's own switch has been flipped by Natsuhiko awakening to his natural talent for giving a woman pleasure, once he "became a man". It's also not altogether inconceivable that, despite her initial rebuttal of his wish to "become a man with her", Mao-nee actually and secretly wanted to do so, perhaps while maintaing dominion over him.
IMHO, There Can Be Only One way to resolve this (know-what-I-mean, know-what-I-mean). But if it never happens in print, here's another grand example of "Sexy Onee-san" ... "AND IT IS GLORIOUS!"