Born in 1570 as the son of Shimazu Iehisa, Shimazu Toyohisa was a nephew of Shimazu Yoshihiro. He became lord of Sadowara Castle in 1588. At the Battle of Sekigahara in 1600, he fought for the Western Army under his uncle Yoshihiro. When the Western Army's defeat became certain, Yoshihiro's Shimazu forces carried out the audacious "Shimazu Withdrawal," breaking straight through the enemy lines with a small band of men; Toyohisa served as rearguard to cover his uncle's escape. Pursued by the forces of Ii Naomasa and Matsudaira Tadayoshi, Toyohisa is said to have fought fiercely as a decoy and fallen in battle, at age 31. His self-sacrificing stand allowed Yoshihiro to make it back to Satsuma.

A bold, valiant young warrior whose loyalty to his uncle Yoshihiro led him to sacrifice himself as rearguard. He showed the composure and courage to fulfill his duty even amid the desperate circumstances at Sekigahara.

Toyohisa's self-sacrificing stand during the "Shimazu Withdrawal" is remembered today as an episode symbolizing the martial valor of the Shimazu clan. The ruins of his residence, Sadowara Castle, are maintained as a historic site in Miyazaki City.