In 1995, Chinese filmmaker Ban Zhongyi set out to meet a woman in a remote part of central China to record her story of sexual enslavement by the Imperial Japanese Army.

He never met her, but after more than a decade of research and over 100 tapes of interviews, he has a made a powerful documentary film about her life and the lives of other women forced into sexual service during Japan's occupation of China in the 1930s and 1940s.

"It was tough, but it was worth it. I don't regret anything at all," the 48-year-old filmmaker said.