Japanese Emperor Akihito and Empress Michiko are to visit the Philippines, in a rare overseas "peace tour" seen as a continuation of efforts to strengthen ties with a former World War II adversary.

The four-day state visit starting on Tuesday marks the 60th anniversary of diplomatic relations between Manila and Tokyo, considered one of the closest allies in the Asia-Pacific region. It also brings back attention to the plight of the Filipinas forced to become sex slaves by Japanese soldiers during the war.

While Japan reached a deal with South Korea last December, offering $8.7m in compensation for war-time sex slavery, there is no similar agreement with the Philippines. That leaves the Filipina victims of abuse, also known as "comfort women", still fighting for justice more than 70 years after their ordeal.

Emmi de Jesus, the women's rights advocate and member of the Philippine Congress, said Akihito's visit would be more meaningful if he meets the victims and personally hears their stories.

"The emperor could be a very strong influence with the Japanese Prime Minister [Shinzo Abe], and could move for action with regards to the demands of the victims," de Jesus told Al Jazeera.

READ MORE: Japan's 'comfort women' battle spills into the US

Last Friday in Manila, a few surviving women now in their 80s told reporters that they want an official apology and compensation from the Japanese government, as well as the inclusion of their stories in official historical records.

"We have yet to achieve justice. We have lost a lot, including our dignity," Narcisa Claveria, 85, was quoted as saying at the press conference.

In an interview with Al Jazeera's Marga Ortigas in Manila, Hilaria Bustamante, 89, recalled how she was repeatedly abused by Japanese soldiers as a 16-year-old girl.

"One Japanese soldier started to rape me while the other two held my arms and legs down. When he was done, the other one started on me - even though I was screaming because of the pain my body was in… They kept at it," she recalled.

For years, many of the women had to repeatedly relive the indignities of their experience as they joined countless protests, appeared in public hearings, and even faced the courts in Tokyo and Manila to secure justice. But nothing has come of their efforts so far.

When a Tokyo court rejected their case in 1998, the judge said that the 1907 Hague Convention on war only honours state-to-state and not individual compensation. The judge also said that the 20-year statute of limitation on making claims had lapsed, and that Japan had already compensated the Philippine government under the 1951 San Francisco Peace Treaty.

Geopolitical calculations

Since the early 1990s, when 200 Filipinas came out in public to tell their stories, the number of victims have dwindled and only about 70 are still alive, many in their mid and late-80s.

According to Lila Pilipina, the organisation representing the victims, at least 1,000 Filipinas were abused by the Japanese soldiers. Throughout Asia, an estimated 200,000 women were reportedly taken as sex slaves.

Victims and critics say the Philippine government shares the blame for the "continuing injustice", and accuse President Benigno Aquino of being beholden to Tokyo.

Japan is a top source of foreign aid and investment in the Philippines. In 2014, trade between the two countries hit nearly $20bn.

Richard Javad Heydarian, a columnist and Asia analyst at De La Salle University in Manila, said Aquino's muted response to the issue of sex slavery reflects his geopolitical calculations, given his feelings towards China.

"This has a lot to do with the Aquino administration's emphasis on building a strong alliance for the future, in light of the Chinese threat," he told Al Jazeera.

But Heydarian said the Philippine government should also watch out for Tokyo's "manifestation of historical revisionism", while maintaining "a steady and strong" strategic and economic partnership.

"One big concern with Abe's administration is the perception that it is historically revisionist and not fully apologetic about Imperial Japan's aggression in early-20th century", including the issue of sex slavery, he said.

Amid Abe's flexing of Japan's muscle and concerns of revisionism, Akihito's visit to the Philippines is relevant as he represents the face of Japan's "soft power", Heydarian said.

While in the Philippines, Akihito is expected to pay tribute to the Filipino victims of World War II, as well as holding a memorial for Japanese soldiers. Akihito had previously visited the Philippines while he was a crown prince.

Meanwhile, de Jesus, the Congress member who has been fighting for justice for the former sex slaves, said she hoped Akihito's visit would serve as a reminder of the futility of military intervention.

"One of our calls is never again to another generation of comfort women," she said.

"Because if there's another military intervention, what happens is there's going to be another cycle of sexual abuse as part and as an instrument of intervention."