Served Nobunaga Oda and distinguished himself in the battles against the Asais, the expedition to the northern provinces and the Nagashino Battle (1575).
He was made Lord of Toyama in Etchu Province. When Nobuo Oda broke with Hideyoshi Toyotomi (1584), Ieyasu Tokugawa supported Nobuo and fought Hideyoshi. Narimasa went to the camp of Nobuo and attacked Toshiie Maeda in Kaga Province but was defeated. After Hideyoshi, Nobuo and Ieyasu made peace, he unsuccessfully urged Ieyasu and Nobuo to get rid of Hideyoshi. Hideyoshi's horde invaded Etchu (1585) and Narimasa, unable to stop it, became a Buddhist priest and surrendered. Hideyoshi transferred him to Higo Province (Kumamoto Prefecture). Due to his misadministration, riots broke out in Higo and Hideyoshi made the Kohayagawas suppress them. Narimasa committed harakiri at Amagasaki near Osaka,as ordered by Hideyoshi.
His daughter married kuge Takatsukasa Nobufusa and they had a son Nobuhisa.