Study world history. European powers and others kept "comfort women" or legitimate military brothels into the 20th century. In the 1970s, there were separate brothels in South Korea for American forces and for Katusas (Koreans attached to the U.S. Army).
Have you ever read "Sandakan Brothel No. 8" — later made into a movie — about a Japanese woman working in such a house? She got paid for her services and sent most of her "dirty" money home to her family, who was more than happy to receive it.
The Korean Peninsula, as part of the Japanese empire during World War II, was just another recruitment area for these women. However, if any of the women were enslaved — not paid for their services — that's another issue.
Don't forget that Korea came under Japanese rule in 1905 and was annexed in 1910. Many Korean men served as soldiers for Japan, not just as laborers. South Korean President Park Chung Hee graduated from the Imperial Japanese Army Academy (and served as a lieutenant in the Manchukuo Army toward the end of the war).
The opinions expressed in this letter to the editor are the writer's own and do not necessarily reflect the policies of The Japan Times.