There were several ranks of prostitutes (yujo) in Japan, and the Oiran were the ones at the top. Japan's licensed quarters were introduced (well, officially speaking) in 1617 and the practices remained in force and little changed until 1957, when the red light districts closed (well, officially speaking) for ever.
The Oiran often enjoyed great fame and fortune. Sold into the profession from childhood, however, they were in reality nothing more than slaves. Every brothel had its Oiran. Every year they joined a big parade called Oiran dochu. In Tokyo's Yoshiwara (now in Asakusa), the oldest red light district, the parade still goes on as a piece of pageantry. Happily, the Oiran is now only one and carefully selected from among the daughters of the local storekeepers' association; the year I saw it last, she was the offspring of a wealthy rice-merchant.
These photographs date from the Taisho period (1912-1926), when girls were still recruited from childhood. Until becoming prostitutes in their teens, they acted as pages to the Oiran and were known as kamuro.
Postcards like these were very popular both in Japan and outside, where the protagonists were often mistaken for geisha. In many cases, the beauty of the pictures, the costumes, the pomp and circumstance entirely fail to mask the tragedy that can still be read on those ostensibly blank white faces.