In 1586 at Hetsugigawa (present Ōnogawa) in Bungo province Toyotomi's vanguard divisions under Chōsokabe Motochika and Sengoku Hidehisa landed on Kyūshū with orders to act defensively until further troops were able to join them.

Motochika proposed a withdrawal, but his companions, Yoshimune and Hidehisa, insisted on doing battle, so the Shimazu set their trap.

The decoy force led by Ijuin Hisanori attacked across the river and then withdrew, which persuaded the allied left wing to follow them.

They were met by arquebus and arrow fire, and the main body of the Shimazu under Iehisa and Tadamoto, then fell upon them.

Chōsokabe Motochika was obliged to signal a full retreat, during which his son Nobuchika and Sogō Masayasu were killed.