Aki Motoyasu served as a bushō during the Sengoku period. He was a kokujin, or provincial landowner, in Tosa Province in Shikoku. Motoyasu served as the lord of Aki Castle in the Aki District of Tosa.
The Aki clan descended from Soga no Akae, the head of a gōzoku, or wealthy family, from the Asuka period in the seventh century who was exiled after the Jinshin Conflict. The Aki were counted among the Seven Great Families of Tosa during the latter part of the Muromachi period and the Sengoku period.
Motoyasu was born as the son of Aki Motochika. By the Tenbun era (1532 to 1555), Motoyasu lost his eldest son and natural heir, Yasuchika, so he was succeeded by his second son, Aki Kunitora. Under another theory, Kunitora was a nephew.
Motoyasu died in 1544. He was interred at the family temple known as the Jōtei Temple constructed by his father, Motochika. The temple name is derived from the posthumous name given to Motochika of Shōchū Jōtei chosen by Motoyasu.