The potato is a versatile tuber, used as a pessary, contraceptive, and masturbatory aid by women, although somehow it always manages to get stuck – at least according to contemporary legend.
Sabine Frühstück, Colonizing Sex: Sexology and Social Control in Modern Japan (Berkeley: University of California Press, 2003), 72.
Many middle- and upper-class educators, physicians, and social reformers suspected female factory workers to be promiscuous and “undutiful.” Physicians who examined female factory workers believed that many of them masturbated regularly. In light of the lack of education among workers in general, they assumed that there were more women in factories than among the upper and middle classes who were prone to sexual indecencies. […]
In 1925, Hosoi Wakizō, the author of The Sad History of Factory Women (Jokō aishi), reported on women who had secretly taken short pieces of pipe home from the factories and inserted them into their vaginas. Others used potatoes for the same purpose and eventually had to see a doctor because the potatoes could no longer be removed. Tall girls pressed their bodies against the machines, thus sexually arousing themselves while working (Hosoi 1996 : 317). […]
Hosoi Wakizō had been working in a factory since the age of thirteen and remained a worker and socialist activist at a cotton spinning factory until his death at the age of twenty-nine. In his book he wrote that female workers and a factory physician with whom he was acquainted had told him these stories.
Hosoi Wakizō. 1996 (1925). Jokō aishi (The sad history of factory women). Tokyo: Iwanami shoten.
Cf. Elissa Henken, "Escalating Danger in Contemporary Legends." Western Folklore 61: 3&4 (Fall 2002): 271; Mariamne Whatley & Elissa Henken, Did You Hear About the Girl Who...? (New York: New York University Press, 2000), 137.