Thea Bisenberger-van der Wal says she still remembers sitting on the steps of a church in Indonesia back in 1944 while waiting for her mother to come out.

Her mother always cried but only told her, then aged 4, that she had fallen.

The mother never spoke to her of what really happened in the church for the rest of her life until she died 10 years ago, Bisenberger said, though she constantly suffered from nightmares because of the indelible experiences: sexual slavery by Japanese troops.

Bisenberger, now living in Canada, provided some details of what her mother went through in a letter to the Asia Policy Point, a nonprofit research center studying the U.S. policy on Northeast Asia. Mindy Kotler, director of the center, disclosed the letter to Yonhap News Agency on Monday.

Bisenberger has been calling for an apology from Japan.

It is not new news that Dutch women were among the victims of Japan's sexual enslavement during World War II, but the case shows the issue still remains unresolved not only for Korean victims but for victims of other countries as well.

At least 65 Dutch women were believed to be among the victims, known euphemistically as "comfort women."

"Not all the comfort women were Korean," Kotler said. "They were pressed into service on every island and territory invaded by Japan. The rapes were proof of victory and power for the Japanese and loss and humiliation for the conquered people."

Bisenberger said she learned of her mother's experiences in 2009 when a younger sister of her mother told her about it. The aunt was the only one to whom the mother revealed what happened because she wanted to spare her mother about the tragic story, Bisenberger said.

"My mother and her sister were raped while in a concentration camp in Moentilan. There was a church on this property and it was the former Xavier college. In this church happened the most horrible things during our captivity," Bisenberger said in the letter of what happened in January 1944.

The horrible experiences left deep scars on their hearts, she said. Her mother's sister even attempted suicide while in the concentration camp, but her mother saved the sister, Bisenberger said.

Bisenberger said that once a year she attends a rally that a group of Dutch people hold every second Tuesday of the month in front of the Japanese Embassy in The Hague.

"After the war, my mother always had nightmares, which never went away," she said. "When a war is over, it's never over for the victims who survive, which is very sad. Even the children will always wonder if the things they have in their heads were real. My mother always tried to erase them." (Yonhap)