He lived during the Sengoku period.
He was the son and successor of Arima Haruzumi and the father of Kirishitan daimyo Arima Harunobu.
[1][2] He was the 12th head of the Arima clan.
[3] In 1563, Yoshisada formed a partnership with the Portuguese and the Jesuits due to the goods they brought to the domain.
In 1576, Yoshisada converted to Christianity, along with some of his subjects.