Excerpt from here.
While serving as a “comfort woman” Ms. Chong Ok Sun witnessed the Japanese torture a Korean girl who asked why they were forced to service up to forty men a day. A Japanese commander ordered her to be beaten with a sword while the other “comfort women” watched. The soldiers stripped the girl, tied her arms and legs, and rolled her over a board covered in nails “until the nails were covered with blood and pieces of her flesh.” She was then decapitated. One Japanese officer told the witnesses that “it’s easy to kill you all, easier than killing dogs” and suggested that the flesh of the dead girl would be boiled and the survivors forced to eat it.
It’s estimated that there were 200,000 comfort women and that only 25% survived (wikipedia article with citations and resources here).