Female Emperors in Japan

I am very interested in the Imperial Family in Japan. All  royal families interest me, but especially the Japanese Imperial Family, because I'm living in Japan.

Currently the law in Japan says that only a male offspring in the male line belonging to the Imperial Lineage may become emperor. In 2004, the prime minister established a group to study the Imperial House Law and questions on succession because there had been four decades with no male births in the imperial family.  The group issued a report in 2005 that recommended female members of the imperial family and matrilineal descendants be able to take the Chrysanthemum Throne. Before Legislators could consider this, Princess Kiko gave birth to Prince Hisahito, and the recommendations were set aside. 

Now people are beginning to call for the government to again consider this recommendation.  There are just three men currently eligible to succeed Emperor Naruhito - his younger brother Fumihito, his fourteen year old nephew Hisahito, and his elderly uncle Masahito. Under the present system, if Hisahito becomes emperor and does not have a son, there will be no possible heir to the throne.  (How's that for pressure?) 

Historically there was no requirement for emperors to be men. There have been eight women who have served as emperor, two serving twice.  All of them were descendants of emperors through the male line.

Empress Suiko (r. 592–628)
The daughter of Emperor Kinmei, she ascended to the throne after the assassination of her predecessor, Emperor Sushun, by a member of the powerful Soga clan. With no immediate agreement on who would succeed, the selection of Suiko, whose mother was also in the Soga clan, was seen as bringing political stability. She oversaw an age in which Buddhism flourished and the temple Hōryūji was built in Nara. Japan also began diplomatic missions to China during her reign.

Empress Kōgyoku (r. 642–645)/Saimei (r. 655–661)
When there was no agreement on succession after the death of her husband, Emperor Jomei, with Soga wishes again a factor, the great-granddaughter of Emperor Bidatsu ascended to the throne under the name of Kōgyoku. She abdicated after a few years and her younger brother became Emperor Kōtoku. However, when he died and there was again no clear candidate to succeed, she ruled again under the name of Saimei.

Empress Jitō (r. 690–697)
The daughter of Emperor Tenji and the wife of her predecessor, Emperor Tenmu, she ascended to the throne as her son Prince Kusakabe had a strong rival to the succession at that time. Kusakabe died shortly after, so Jitō ruled until her grandson was old enough to succeed her as Emperor Monmu.

Empress Genmei (r. 707–715)
A younger half-sister of Empress Jitō and daughter of Emperor Tenji, she was also the wife of Prince Kusakabe and mother of Emperor Monmu. She ascended to the throne as her grandson (later Emperor Shōmu) was too young to succeed at the time of Monmu’s death.

Empress Genshō (r. 715–724)
The only woman to follow a woman in the imperial succession, she was the daughter of Empress Genmei. As her father was Prince Kusakabe, the son of Emperor Tenmu, she was also in the male imperial line. She ascended the throne when Genmei abdicated after nine years and the future Emperor Shōmu was still seen as too young to succeed.

Empress Kōken (r. 749–758)/Shōtoku (r. 764–770)
The daughter of Emperor Shōmu, she became the first woman to be officially designated as the first in line to the throne when his son died an early death. She ascended to the throne under the name Kōken but later abdicated, with her cousin becoming Emperor Junnin. During his reign, a power struggle intensified between him and the retired Kōken, backed by the Buddhist monk Dōkyō, who became a powerful favorite of hers. When Junnin’s supporter Fujiwara Nakamaro attempted to raise a rebellion to win back authority, her forces were victorious. She dethroned Junnin and took the throne again to rule for six more years as Shōtoku.

Empress Meishō (r. 1629–43)
She succeeded her father, Emperor Go-Mizunoo, who had no sons at the time he abdicated following a dispute between the Tokugawa shogunate and the imperial court. However, he had a son after his abdication, and she later gave up the throne herself when the boy was old enough to become Emperor Go-Kōmyō.

Empress Go-Sakuramachi (r. 1762–70)
The daughter of Emperor Sakuramachi, she ascended the throne after the death of Emperor Momozono as his designated successor was still too young to become emperor. She later abdicated and the boy became Emperor Go-Momozono.

Source: Nippon.com