Until recently, Kim Soon Duk never spoke about her experience as a sex slave for Japanese soldiers during the war.

Not even her closest family members knew that Kim spent three years in Shanghai and Nanjing as a sex slave, rather than as a conscripted factory worker in Japan, as she had been led to believe before being shipped off from South Korea to China.

In 1940, aged 19, Kim returned home to recover from a serious illness after receiving permission from a high-ranking officer.

From that time on, Kim, like thousands of other women from the Korean Peninsula forced to work as "comfort women" in Japanese brothels, tried to bury her painful past in silence.