The formal term for wartime sex workers in Japanese is juugun ianfu, or frontline comfort women. In everyday parlance, the noun ian alone refers to recreation, such as company-sponsored R&R or facilities provided by companies as an incentive or to show appreciation to employees.

During the war, ianfu were installed in "comfort stations" across Asia, operated either directly by or under the aegis of the Japanese military.

While prostitution around military encampments has existed throughout history, imperial Japan's institutionalization of military brothels was notable for its enormous scale and cold, efficient brutality. Digging into defense archives, Chuo University scholar Yoshiaki Yoshimi unearthed irrefutable evidence of how the imperial and military authorities procured women much like rations or rifles, often recruited with