, according to the traditional order of succession.
Kōgyoku's reign spanned the years from 642 to 645. Her reign as Saimei encompassed 655 to 661. In other words,
• 654: Kōtoku died and the throne was vacant.
• 661: Saimei ruled until her death caused the throne to be vacant again.
The two reigns of this one woman spanned the years from 642 through 661.
In the history of Japan, Kōgyoku/Saimei was the second of eight women to take on the role of empress regnant. The sole female monarch before Kōgyoku/Saimei was Suiko-tennō. The six women sovereigns reigning after Kōgyoku/Saimei were Jitō, Genmei, Genshō, Kōken/Shōtoku, Meishō, and Go-Sakuramachi.
Traditional narrative
Before her ascension to the Chrysanthemum Throne, her personal name (imina) was . As empress, her name would have been .
Princess Takara (Takara no miko) was a great-granddaughter of Emperor Bidatsu.
Events in Kōgyokus reign
During her first reign the Soga clan seized power. Her son Naka no Ōe planned a coup d'état and slew Soga no Iruka at the court in front of her throne. The Empress, shocked by this incident, abdicated the throne.
Kōgyoku's contemporary title would not have been tennō, as most historians believe this title was not introduced until the reigns of Emperor Tenmu and Empress Jitō. Rather, it was presumably Sumeramikoto or Amenoshita Shiroshimesu Ōkimi (治天下大王), meaning "the great queen who rules all under heaven". Alternatively, Kōgyoku might have been referred to as (ヤマト大王/大君) or the "Great Queen of Yamato".
Empress Kōgyoku reigned for four years. The years of Kōgyoku's reign are not linked by scholars to any era or nengō. The Taika era innovation of naming time periods – nengō – was yet to be initiated during her son's too-brief reign.
In this context, Brown and Ishida's translation of Gukanshō offers an explanation about the years of Empress Jitō's reign which muddies a sense of easy clarity in the pre-Taiho time-frame:
:"The eras that fell in this reign were: (1) the remaining seven years of Shuchō (686+7=692?); and (2) Taika, which was four years long 695–698. (The first year of this era was kinoto-hitsuji 695.) ... In the third year of the Taka era 697, Empress Jitō yielded the throne to the Crown Prince."
The years of Kōgyoku's reign are not more specifically identified by more than one era name or nengō which was an innovation of Kōtoku's brief reign.
Events in Saimeis reign
When Kōtoku died, his designated heir was Naka no Ōe. When Naka no Ōe's mother re-ascended, he continued in the role of her heir and crown prince. In this role, he could and did remain active in the political life of Japan.
In the fifth year of Saimei's reign, Paekche in Korea was destroyed in 660. Japan assisted Paekche loyals in an attempt to aid the revival of Paekche dynasty. Early in 661, Saimei responded to the situation by leaving her capital in Yamato Province. Her plan was to lead a military expedition to Korea. The empress stayed in Ishiyu Temporary Palace in Iyo Province, today Dōgo Onsen. In May she arrived at Asakura Palace in the north part of Tsukushi province in Kyūshū, today a part of Fukuoka Prefecture. The allied army of Japan and Baekje was preparing for war against Silla, but the death of the empress thwarted those plans. In 661, Saimei died in the Asakura Palace before the army departed to Korea. In October her body was brought from Kyūshū by sea to Port Naniwa-zu (today Osaka city); and her state funeral was held in early November.
Empress Saimei ruled for seven years. The years of Saimei's reign are not linked by scholars to any era or nengō. The Taika era innovation of naming time periods – nengō – languished until Mommu reasserted an imperial right by proclaiming the commencement of Taihō in 701.
The actual site of Kōgyoku/Saimei's grave is known, having been identified as the Kengoshizuka tomb in the village of Asuka, Nara Prefecture. This empress is traditionally venerated at a memorial Shinto shrine (misasagi) at Nara.
The Imperial Household Agency designates this location as Kōgyoku/Seimei's mausoleum. It is formally named Ochi-no-Okanoe no misasagi.
Kugyō
Kugyō (公卿) is a collective term for the very few most powerful men attached to the court of the Emperor of Japan in pre-Meiji eras.
In general, this elite group included only three to four men at a time. These were hereditary courtiers whose experience and background would have brought them to the pinnacle of a life's career. During Kōgyoku's reign, this apex of the Daijō-kan included:
• Sadaijin
• Udaijin
The kugyō during Saimei's reign included:
• Sadaijin, Kose no Tokoda(巨勢徳太) (593–658), 649–658
• Udaijin (not appointed)
• Naidaijin (内臣), Nakatomi no Kamako(中臣鎌子) (Fujiwara no Kamatari, 藤原鎌足) (614–669), 645–669
Spouses and Children
• First Husband: Prince Takamuku (高向王), Prince Tame's son (also Emperor Yomei』s grandson)
• First Son: Prince Kara (漢皇子)
• Second Husband: Prince Tamura (田村皇子) later Emperor Jomei, Prince Oshisaka-no-hikohito-no-Ōe's son (also Emperor Bidatsu』s grandson)
• Second Son: Prince Naka no Ōe (中大兄皇子) later Emperor Tenji)
• First Daughter: Princess Hashihito (間人皇女, d. 665), married Emperor Kōtoku
• Third Son: Prince Ōama (大海人皇子) later Emperor Tenmu
皇極天皇（；594年 - 661年），日本第35代和第37代天皇。為日本第二位女性天皇。諱寶女王（），後世又尊稱為寶皇女。皇極天皇是她第一次在位期間的稱號（642年1月15日至645年6月14日）。第二次在位期間（655年1月3日至661年7月24日）稱齊明天皇（）。