In 1583 he became a vassal of Toyotomi Hideyoshi. Terumoto sent the 'Two Rivers' (Kobayakawa and Kikkawa) to lead troops for Hideyoshi in his Invasion of Shikoku (1585) and Kyushu Campaign (1587). He sent ships to assist Hideyoshi in his reduction of the Hojo at Siege of Odawara (1590). When Hideyoshi invasion Korea in 1592, Terumoto himself led a 'Division' of troops there, although much of his time seems to have been taken up fighting Korean partisans.