>>253
I remember reading this one doujin where akko was surprised by diana's pink nipples, because being purebred white british (and from a very "good breeding" pedigree), she has pink nipples, and not the comparatively more brown-ish ones that east asians have.
It's little details like that which has some charm to it.
It tells us two things, the first being that akko is quite pure, the only nipples she's seen are likely those of herself and her family (japanese culture is big on sharing baths), and if she watched porn, she'd know what to expect from a caucasian girl's chest.
The second is that the cross-racial relationship has a bit of a thrill to it coming from the interracial aspect of it, in addition to the fact that these are enemies-turned-rivals-turned-friends-turned-lovers, and in addition to the fact that their relationship is considered contentious in universe due to diana's family and their expectations (as a member of the upper class, she'd be expected to enter a heterosexual relationship rather and a homosexual one), the class differences between diana and akko (wealthy vs poor), the differences between them as witches (one born from a family of legendarily powerful mages, one born from humans with no magical ability whatsoever), and differences in their philosophy of magic (protecting tradition and staying safe vs embracing innovation and risking danger, keeping magic to a insular elite as their protected secrets vs sharing magic even with those incapable of using it, having magic be useful and restricted to absolute necessity vs making a vulgar show of it and using it all the time).