Josei Tennō in the context of "Crown Prince Akishino"

In Japan, the Sesshō (摂政) was a regent who was named to act on behalf of either a child emperor before his coming of age, or an empress regnant. The Kampaku (関白) was theoretically a sort of chief advisor for the Emperor, but was in practice the title of both first secretary and regent who assisted an adult emperor. The duties of the Sesshō and Kampaku were to convey to the Emperor the policies formulated by the Sadaijin (左大臣, Minister of the Left) and other senior officials of the Daijō-kan (太政官, Council of State), and to convey the Emperor's decisions to them. As regents of the Emperor, the Sesshō and Kampaku sometimes made decisions on behalf of the Emperor, but their positions were not defined by law and they had no specific political authority. The two titles were collectively known as sekkan (摂関), and the families that exclusively held the titles were called sekkan-ke (sekkan family).

During the Heian period (794–1185), from the middle of the 9th century, the Fujiwara clan began to marry off their daughters to the Emperor and assume the positions of Sesshō and Kampaku, thereby excluding other clans from the political centre and increasing their political power. From the 10th century, the Fujiwara clan monopolized the Sesshō and Kampaku, and at the end of the 10th century, around the time of Fujiwara no Michinaga and Fujiwara no Yorimichi, the power of the Fujiwara clan reached its zenith. In the mid-11th century, Emperor Go-Sanjo ran his own government, and the next Emperor, Shirakawa, abdicated to become Cloistered Emperor, beginning the cloistered rule. From then on, the cloistered rule of Cloistered Emperor took root, and the de facto Fujiwara regime, which used the positions of Sesshō and Kampaku, was over, and the Sesshō and Kampaku lost their real political power and became mere names.

Empress Genmei (元明天皇, Genmei-tennō; April 20, 660 – December 29, 721), also known as Empress Genmyō, was the 43rd monarch of Japan, according to the traditional order of succession. Genmei's reign spanned the years 707 through 715. She established the capital at Heijō-kyō in 710, marking the beginning of the Nara period.

In the history of Japan, Genmei was the fourth of eight women to take on the role of empress regnant. The three female monarchs before Genmei were Suiko, Kōgyoku/Saimei, and Jitō. The four women sovereigns reigning after Genmei were Genshō, Kōken/Shōtoku, Meishō, and Go-Sakuramachi.

Empress Kōken (born Abe, known as Empress Shōtoku during her second reign; 718–770) was the 46th and 48th monarch of Japan according to the traditional order of succession. She was born to Crown Prince Obito (the future Emperor Shōmu) and his consort Fujiwara Asukabehime; seeking to protect the bloodline of Prince Kusakabe, her father proclaimed her the first crown princess in Japanese history in 738. She became the Empress Regnant in 749, after her father retired to become a Buddhist monk. With the backing of her mother (now Dowager Empress Kōmyō) and her mother's nephew Fujiwara no Nakamaro, she was able to outmaneuver a largely hostile Daijō-kan (Council of State). Her father died in 756, having named a cousin unrelated to the Fujiwara as her heir; this outraged Fujiwara supporters, and Kōken replaced him with Prince Ōi, a close ally of her mother and Nakamaro. In 757, she headed off a conspiracy to overthrow her by Tachibana no Naramaro, and resigned the following year to serve as empress emerita (Daijō Tennō), while Ōi reigned as Emperor Junnin.

Nakamaro slowly consolidated his political power with the backing of dowager empress Kōmyō. After an illness, Kōken became close to a healer-monk named Dōkyō, who became one of her strongest allies, as well as potentially an intimate partner. After this, she became a bhikkhunī (Buddhist nun) and shaved her head. After her mother's death in 760, Kōken began to oppose Nakamaro. She proclaimed superiority over Emperor Junnin in state matters in 762, and allied with anti-Nakamaro leaders, including her childhood tutor Kibi no Makibi. In 764, political conflict grew violent after she attempted to take control of the royal seals; Nakamaro fought a brief rebellion against her, naming Prince Shioyaki as emperor, but both were captured and executed, and Kōken returned to the throne as Empress Shōtoku.

Empress Suiko (推古天皇, Suiko-tennō) (554 – 15 April 628) was the 33rd monarch of Japan, and the country's first and longest-reigning empress regnant, according to the traditional order of succession.

Suiko reigned from 593 until her death in 628.

Empress Genshō (元正天皇, Genshō-tennō; 680 – May 22, 748) was the 44th monarch of Japan, according to the traditional order of succession. Her reign spanned the years 715 through 724.

Genshō was the fifth of eight women to take on the role of empress regnant, and the only one in the history of Japan to have inherited her title from another empress regnant rather than from a male predecessor. The four female monarchs before Genshō were Suiko, Kōgyoku, Jitō and Genmei; the three reigning after her were Kōken, Meishō, and Go-Sakuramachi.

Aiko, Princess Toshi (敬宮愛子内親王, Toshi-no-miya Aiko Naishinnō; born 1 December 2001) is a member of the Imperial House of Japan. She is the only child of Emperor Naruhito and Empress Masako.

Following her birth, the ongoing Japanese imperial succession debate had resulted in some politicians holding a favorable view on rescinding agnatic primogeniture (male-only imperial succession) originally implemented in 1889 and retained by the Allies of World War II on the Constitution of Japan. However, once her uncle Crown Prince Fumihito had his son, Hisahito, in September 2006, Hisahito became second in the line of succession following his father. Aiko remains at present legally ineligible to inherit the throne and she cannot succeed her father, while debate about the possibility of having future empresses regnant continues.