In 1570, Naoshige assisted Takanobu while at Saga Castle when it was surrounded by a 60,000-man Ōtomo clan army.

In 1575, he attacked Suko Castle in western Hizen and forced its commander, Hirai Tsuneharu, to commit suicide.

[6][7] However In April 23, two Ōtomogenerals Tachibana Dōsetsu and Takahashi Shigetane engaged the allied forces with the combination of skillful artillery salvos, defensive formation tactics, and timely counterattacks, which in the end caused the allied siege collapsed.

[8][9] In 1587, Naoshige took this chance of having a weak heir to leave the Ryūzōji and to support Toyotomi Hideyoshi while during his battle against Kyūshū.

In 1592, he was sent on Hideyoshi's Korean campaigns where he struck up a friendship with Katō Kiyomasa and upon his return to Hizen, with Tokugawa Ieyasu.