Overview
As a tag of pixiv, it is often used for so-called ethnic works (exotic, mainly in the style of named minorities).
It's worth mentioning that, in Europe and America, "Nationality" is often used to the legal connection or bond between an individual and a particular country and his or her eligibility to become a citizen of that country.
But in East Asia, "Nationality" refers to a community of humans who are separated from others by certain cultural characteristics, such as the Chinese nationality and Japanese nationality, which are composed of several ethnic groups.