Iyo (or Toyo, depending on the particular reading of historical texts) was a shaman queen of Yamatai; a nation of Japan's Yayoi period. What few surviving records of the era indicate that she was installed into the position at the age of thirteen. In 248, the previous queen, Himiko, had passed away and was briefly succeeded by a male king. However, this king was quickly overthrown and cast out or assassinated.
Iyo's specific relationship to Himiko is not known, though some speculate that she may be her niece.
In Video Games
Toukiden: The Age of Demons
Iyo appears in Toukiden as one of the numerous mitama in the game; souls of Japanese historical figures that the player can equip and power up.