Seoul (CNN) -- Every single week for the past 22 years, a group of elderly South Korean women has camped outside the Japanese Embassy in Seoul, enduring the heat and humidity of the region's monsoonal summer and the sub-zero temperatures of the brutal Korean winter.
They want an apology for being forced into sexual slavery as so-called "comfort women" by the Japanese military before and during World War II -- an apology that numerous Japanese governments insist has already been publicly given more than two decades ago.
It has been almost 70 years since the end of World War II and yet this issue still has the power to derail relations at the very top of these two countries.
The issue of "comfort women" is expected to be discussed when officials from Tokyo and Seoul meet Wednesday in an effort to improve frosty relations ahead of President Obama's tour of the region next week.
Japan's Prime Minister Shinzo Abe and South Korean President Park Geun-hye only met for the first time since both taking power last month. And only then because it was organized and led by U.S. President Barack Obama, eager to heal the rifts of his country's two closest allies in the region.
The two governments "have decided to engage in intensive discussions on various subjects at various levels" to improve conditions surrounding relations, the Japanese foreign ministry said in a statement.
The issue of comfort women is an emotive one that ignites passions in both countries. Many of these women have already passed away. Only 55 of those registered with the South Korean government are still alive.
A small, but vocal voice within the Japanese opposition has been calling for a revision of the Kono statement made in 1993 -- a statement made by then Chief Cabinet Secretary Yohei Kono that accepted Japan's responsibility for recruiting "comfort women" and extended "its sincere apologies and remorse."
It is this statement Hiroshi Yamada of the Japan Restoration Party wants changed.
"We are not saying the Kono statement should be nullified because we dislike it or it is irritating to the Japanese people," he said. "Japan had state-run prostitution just like other countries in the world around World War II and we admit that there were unfortunately women working there."
Abe diluted this argument recently when he insisted Japan would not retract its apology. "I am deeply pained to think of the comfort women who experienced immeasurable pain and suffering, a feeling I share equally with my predecessors," he said.
But the suggestion that up to 200,000 women, mainly Korean, used by the Japanese military, were official prostitutes infuriates the former sex slaves. They insist they were forcibly taken from Korea or tricked into leaving, thinking they were being transferred to other jobs.
Kim Bok Dong, 89, says she was transported to half a dozen countries over eight years by the Japanese military from the age of 14.
"Every Sunday, soldiers came to the brothel from 8 a.m. until 5 p.m. On Saturday, from noon until five, plus weekdays," she said. "I could not stand at the end of the weekend. I was physically broken."
Saying the Japanese military destroyed her life, she is furious at the minority in Japan calling the accounts of "comfort women" into question.
"I think they are mad," she said at the weekly protest. "You cannot lie with a sane mind. Maybe they are senile to be saying such absurd things."
The issue remains heavily divisive between the two nations.
"The issue of sex slaves is no longer in the hands of the South Korean government," said Yang Kee Ho, a professor at Sungkonghoe University in Seoul. "As long as 55 former sex slaves are alive... the issue lies in the hands of the South Korean public. They want the Japanese government to acknowledge, apologize, compensate and educate their children that their government has committed the crimes of forcing young Korean girls to sex slavery.
"No South Korean government can ignore or deviate from such national consensus without risking losing public support."
Yang said Japan also disagrees with South Korea's efforts to make this an international issue, believing it should be dealt with bi-laterally. Wednesday's meeting between the two countries is certainly a start, but as the first such meeting, one that is expected to reap little in the short term.
Hajime Izumi, a professor at Shizuoka University in central Japan, insisted more time and a generational change is needed before a resolution can be hoped for. "This is not that old an issue," he said. "This issue only really came up in the 1990s and Japan and South Korea are looking at the issue from totally different perspectives. They can never agree while there is such a large gap in perception. It may not be resolved for 20 years."