What kind of woman was Yae, the wife of Yoritomo and Yoshitoki in "The 13 Lords of the Kamakura"? Did she even exist in real life?

Yae was portrayed as "Yoritomo's first wife" in the historical drama "The 13 Lords of the Kamakura" and later became the wife of Hojo Yoshitoki. Many people may have wondered, "Did Yoritomo have other wives besides Hojo Masako?" and were surprised that she ended up marrying Yoshitoki as well, which is quite a dramatic turn of events. However, it's not as if screenwriter Mitani is completely crazy; she is someone who can be portrayed quite freely…