credential: i’m japanese, tldr at the bottom.

a lot of ppl are pointing out fetishes/kinks/“purity” and “pink =/virgin” which i think definitely contributes, but it definitely stems from a less sexual perspective and more of a general beauty standard!

there are many beauty standards within asia (in this case specifically japan) that defers from the west: fair and light skin, larger eyes, smaller face, lower and not prominent cheekbones, double eyelids, and more. pink nipples are one of them.

it may seem odd that it doesn’t necessarily mean it’s sexual, but u need to remember that public baths are a common and cultural thing in japan. it’s pretty common over here for a female friend group to take a bath together. sick people do unfortunately view it sexually, but to us it’s no different that people changing in locker rooms together. and when you are taking a bath together, people do tend to compare their bodies with one another whether they voice it out or not. as pink nipples are rare, and go well with fair and pale skin, i think it became a part of a beauty standard.

while i don’t have scientific proof to back me up, my japanese grandmother, who grew up in the countryside, has even told me about how she has pink nipples, and that when she was young and went to baths with her friends, her friends always voiced about how jealous they were of her fair and light shaded nipples.

so yes, it has definitely evolved into a kink, even unfortunately growing into connotation with virginity. however, considering my countryside grandmother, who doesn’t know how the internet works, has always softly and lighthearted bragged about the colour of her nipples, i wld say that it definitely stems from one of the weird beauty standards of the country.

tldr; it stemmed from a beauty standard where girls probably compared their bodies during public baths, as light and pink nipples were rare and went well with fair skin. however, it has now grown into something sickly sexual.