Tadamasa defeated the Ito in 1485 in southern Hyuga. He suffered the rebellion of a number of Shimazu vassals in Ôsumi in 1496 and the Kimotsuki in 1506. He died in 1508, possibly by suicide.
References
Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005