A priestess of Hera, daughter of the river god Inachus .One day, Zeus noticed the maiden, and he lusted after her. Some say she rejected his advances until he caused her own father to drive her out into the fields. Here, Zeus covered her with clouds to hide her from the eyes of his jealous wife, Hera, who nonetheless came to investigate. In a vain attempt to hide his crimes, Zeus turned himself into a white cloud and transformed Io into a beautiful white heifer. Hera was not fooled. She demanded the heifer as a present.
 In Game
In Persona 3, Io was Yukari's first Persona. She first summoned it to fight against a powerful shadow, but because she did not have total control of Io's powers, she missed. Io is mostly used as a healer, although she does have some Garu skills. After finding out the truth about her father's real message, Io gave rise to Isis.
Persona 3: Dia, Patra, Garu, Charmdi, Magaru, Media, Diarama, Recarm, Garula, Me Patra, Mediarma, Magarula