Empresses ruled Japan at various times over several centuries until they were barred in 1889.

Female rulers

Archeological studies of tombs show that female chieftains were prevalent in western Japan in the fourth century, according to Chizuko T. Allen, a historian at the University of Michigan.

While the tradition of female rulers and chieftains was commonplace in ancient Japan, Shillony says history books tend to emphasize the feats of male emperors.

"Even if the female empress achieved many things, they are still not regarded as prominently as the male emperors," he says.

Some historians maintain the empresses were merely puppet rulers who abdicated once a suitable male heir came of age. Others say they shaped Japan's history more than their male counterparts.

"From today's perspective, it's interesting to think of how the contribution of Japan's past reigning empresses to history has become so diminished," says University of Michigan historian, Hitomi Tonomura.

"By totally ignoring these women or interpreting their roles as mere 'fillers' between (Imperial) men, Japanese society offers no historical imagination for what women can be and do."

Modern Japan

As Japan modernized during the Meiji era of 1868 to 1912, the leaders of the time changed the role of the emperor, reinstating him as military commander-in-chief. -

Because a woman could no longer command the military, Meiji leaders believed it would make no sense to have reigning female empresses, says Shillony. A male-only succession was established.

The desire to emulate the West was also strong.

Meiji leaders took inspiration from the Prussian constitution -- which forbade women from ascending the throne -- and in 1889 barred women from being enthroned, says Shillony. They did not wish to replicate the British model where Queen Victoria reigned.

Instead, the period saw a masculinization of the emperor and of Japanese society in general as the Meiji regime emphasized the perceived superiority of men over women.

"In the Meiji constitution, the notion of 'ie' (house) was inscribed. That subordinated wives and household members under one patriarch. This wasn't the case before," says Tonomura, the historian.

US influence

The US occupation following Japan's defeat in WWII brought changes to society as American values were slowly introduced.

"The US didn't want to alienate the Japanese establishment by diminishing the emperor's status," says Shillony. "People thought the question of gender in the Imperial family should be dealt with by future governments."

Under current law, only male heirs with emperors on their father's side can succeed to the throne. The panel's report suggested a legal change either to allow a female monarch or to reinstate members of the old aristocracy who were stripped of their royal status after WWII.

Unreformed Chrysanthemum Throne

The debate on whether to let women who marry commoners remain within the imperial family has also resurfaced.

But female leadership remains elusive overall in Japan despite moves by the government to empower working women under a scheme dubbed "womenomics."

Unconscious gender bias and male entitlement are still pervasive in Japan, says Tonomura.

And despite the legacy of powerful female rulers, the prospect of a modern-day equivalent is remote without significant moves to redress gender inequality.

"Some women think having a female emperor might be good as a kind of role model," says Tonomura. "But getting a female monarch is wishful thinking at this time."

The only likely change to the monarchy in the near future is one allowing princesses to stay in the Imperial family even if they marry a commoner. That could potentially, says Shillony, pave the way for a female succession in the future.