From Liminality of the Japanese Empire: Border Crossings from Okinawa to Colonial Taiwan, by Hiroko Matsuda (U. Hawaii Press, 2018), Kindle loc. ~1980:
Of the total number of Japanese domestics in Taiwan, 27 percent came from Okinawa Prefecture. The October 1924 edition of Yaeyama News also reported that the Yaeyama Islands were known as a “supplier of maids” to Japanese settler communities in Taiwan: “It seems that the number of Yaeyama girls migrating to Taiwan has increased rapidly of late. Each ship carries more than ten migrants to Taiwan; many of them live as apprentice maids (jochū bōkō [女中奉公]). As people associate maids (gejo [下女]) with Yaeyama girls, Yaeyama is now known as a supplier of maids.”
Domestic service has a long history in Japan. It remained one of the most popular occupations for Japanese women until the 1940s. Before the word jochū became common in the early twentieth century, a domestic was usually called gejo in Japanese, which literally means “under woman.” Until the nineteenth century, a young Japanese woman did not necessarily become a domestic in order to make money. Rather, she worked for an upper-class family as an apprentice servant so that she could learn proper manners and etiquette. By practicing good manners and having a solid grounding in traditional Japanese etiquette, a young Japanese woman from a less prosperous background could prepare herself for marriage. This folk educational custom continued to be practiced even after the state introduced universal education.
The nature of the female apprenticeship was transformed during the interwar period. Instead of becoming an apprentice servant, a young woman could go to technical school or advanced girls’ school (kōtō jogakkō [高等女学校]) and learn cooking and sewing before marriage. Domestic service was no longer the only way for a woman to earn a respectable living. She could take better-paying jobs in an office or factory. As women came to have more educational and professional options in the interwar period, domestic service lost its appeal both as an apprenticeship and as an occupation.
However, the demand for domestics increased in the early twentieth century. Until the nineteenth century, domestics were employed mostly by upper-class households. With the rapid economic development and growth of the interwar period, a new middle class emerged, and its members became the employers of domestics. Of the 10,589,403 working women in Japan in 1930, 697,116 were domestics. A majority of these domestic workers are supposed to have been maids (jochū). Domestics were also in great demand in colonial Taiwan, where government officials, freelance workers, and merchants composed a large majority of the Japanese migrant population. The Taiwan Daily News reported in 1923 that domestics were in high demand and that the Taihoku [Taipei] Employment Agency was listing their average wages at fifteen to twenty-five yen.