In 1589, his biological child Tsurumatsu was born, and Hideyoshi had decided Tsurumatsu to be his successor, however, soon after Hideyoshi achieved the unification of the whole country in 1590, Hidenaga and Tsurumatsu died successively in 1591.
1589年には実子鶴松が生まれ、後継者と定めていたが、1590年に天下統一を果たした直後の1591年には秀長と鶴松が相次いで死亡する。