Osaka Mayor Hirofumi Yoshimura has vowed to snap his city's six-decade sister-city relationship with San Francisco in protest against the US city accepting a statue of "comfort women" as public property.

"Comfort women", a euphemism for some 200,000 girls and young women who were coerced, kidnapped, sold or captured to be sexually exploited in Japan's military brothels before and during World War II, is a taboo term for many in Japan. And these people have been trying to sweep the issue under the carpet.

The statue in San Francisco features three women－a Chinese, a Korean and a Filipina－with the two words, "sex slaves" inscribed on a plaque. Yoshimura has written several letters to his San Francisco counterpart Edwin Lee this year, saying some historians don't recognize the historical facts about "comfort women".

Ikuhiko Hata is one of those historians. In an interview with Yasuo Naito, editor in chief of Japan Forward, Sankei Shimbun's English-language website, Hata said the Republic of Korea uses the "history war" as a weapon and women were not abducted to be sexually exploited. He said that his research shows the women who worked in the "comfort stations" were not "sex slaves" and did not live under the cruel conditions.

Hata also said the wartime newspapers in Seoul carried advertisements for recruiting "comfort women", and the recruiters were not Japanese but Koreans. And he claims that the majority of "comfort women" in Japan and Korea were professional prostitutes. The "comfort women" earned 300 yen ($2.7 now) every month, he said, while Japanese soldiers were paid on average 10 yen.

In 1991, some Japanese lawyers said "comfort women" were "sex slaves" and took the issue to the United Nations Human Rights Council.

Hata blamed some Japanese media outlets such as the Asahi Shimbun for spreading "fake news" about "comfort women" with the help of the Japanese lawyers, which was then drummed up into a worldwide issue.

In Hata's words, those women who endured a half century of humiliation and trauma, and yet had the courage to speak up, and those activists who helped dig out the truth and struggled to get the "comfort women" justice and respect were lying for personal or political reasons.

If the "findings" of historians such as Hata are true, Tokyo should not have signed an agreement with Seoul in 2015 to apologize to and compensate Korean "comfort women".

With the agreement, Japan wanted to bury the issue.

The "comfort women" issue, however, is not a "dispute" between Japan and the ROK alone. Jan Ruff-O'Herne, a Dutch Australian, was taken from an Indonesian prisoner-of-war camp where she was living with her family during Japanese occupation. Ruff-O'Herne fought shame to speak up and became an advocate for women's rights.

When Japanese Prime Minister Shinzo Abe visited the Philippines in January, surviving Filipina "comfort women" asked for a formal apology and compensation from Japan for the atrocities they suffered at the hands of Japanese soldiers during occupation.

Former US congressman Mike Honda took the statue in San Francisco as a physical representation of something that happened in the past that needs to be learned about to prevent violence against women and end human trafficking.

But the Japanese government refuses to look into the country's dark past. After the ROK parliament designated Aug 14 as a day to commemorate Korean "comfort women", Japan criticized the move, saying it violated the spirit of the 2015 agreement. On Aug 14, 1991, Kim Hak-soon, a surviving "comfort woman", became the first to speak about her ordeal. Hundreds of others followed her.

Japan considers any occasion to pay respects to the "comfort women" in other parts of the world as a disgrace to itself. But it allows the country's right-wingers to demean the now elderly survivors and those who died carrying the Japanese insult that "comfort women" were nothing more than professional prostitutes.

Japan's attitude makes the 2015 agreement more like hush money for the ROK than a sincere apology for exploiting innocent women.

The author is China Daily Tokyo bureau chief. caihong@chinadaily.com.cn