In S01E05 of the TV show MASH ("The Moose") a US GI is discovered to have purchased a young Korean woman as a personal slave/servant. They referred to here as "his moose" in the episode. Did this kind of thing actually happen?
The word was bastardized by Americans and comes from the Japanese "musume" which roughly means young girl.
It does not necessarily mean she was a slave or abused but she was a servant.