The New York Times article about Japan's wartime sex slaves (euphemistically called comfort women) notes that upon defeat in WWII, Japan destroyed many of its incriminating documents. Yet some had survived as evidence that through the 1930's & 40's it was an officially established operation by the military:
"Between 50,000 and 200,000 women from Japan, Korea, Taiwan, China, the Philippines, Indonesia and elsewhere were tricked or coerced into sexual slavery."

Yet Japanese revisionist efforts continue to deny or hide this history from their educational system. Certainly this would not be condoned by modern Japan, but this is a history that should not be ignored.