Matt of No-sword has an essay of that title over at Néojaponisme (“We too are non-Japanese inspired by Japanese culture, and we too hope to advocate Japanese products and creative culture that may have been devalued or ignored in Japan”), and it’s a corker. Nanpa is familiar as a term for guys offering public compliments to gals (what they call piropo in Argentina), but it started out very differently:
Nanpa apparently dates back to Edo time but was certainly in popular use during the Meiji period. Back then, it was written in kanji (軟派) and used in relation to its antithesis — kōha (硬派). The words mean “soft faction” and “hard faction,” respectively, and at the time, denoted diametrically opposed philosophical outlooks. Softs were thoughtful, introverted and open to compromise; Hards were aggressive, inflexible, and beat up Softs for kicks.
You can find numerous examples of the words nanpa and kōha being used to bisect various social groups, ranging from newspaper reporters (Softs did society and the arts, Hards did politics) to black marketeers operating in early 20th-century China (Softs dealt drugs, Hards ran guns). The usage that eventually evolved into the modern meaning, however, was the one that applied to young men. Simply put: Softs liked women, and Hards didn’t.
Read his piece for more of this fascinating history.