Jingu Kogo, or Empress Consort Jingu, was believed to have ruled Japan in the late 100s and early 200s CE as regent. Her story is considered by some to be a part of history with some embellishments, and by others to just be the product of legend. She was the wife of Emperor Chuai, the fourteenth emperor of Japan, who reigned from 192—200 CE. In the year 200, Empress Jingu reportedly began a conquest of Korea without shedding a drop of blood (the bloodless part of this is perhaps very much a product of legend). During these times she was pregnant with the fifteenth emperor, Ojin, who was later created as a deity.
In 1889 she was the first woman whose picture was featured on a banknote in Japan.
Note: It is altogether possible that she existed, perhaps with a different name, or during a different time period. There is evidence of some Japanese societies that were matriarchal during around this time, so the prospect of a woman empress would not have been that strange. I would argue that before we can write her off as fiction, to remember that many women’s accomplishments and stories have been shoved under the rug by patriarchal societies and written off as “legend” or “myth”.