Nasu Sukekuni served as a bushō during the Sengoku period.

Sukekuni was born as the third son of Nasu Masasuke, the eighteenth head of the Nasu clan of Shimotsuke Province.

Initially, Sukekuni received as his formal wife the daughter of Fukuhara Sukemori, becoming an adopted son-in-law and head of the Shimotsuke-Fukuhara clan to him.  Later, he adopted Suketaka, the second son of Ōtawara Sukekiyo, and transferred the headship of the Fukuhara clan.  His older brother, Nasu Suketane, first inherited the Morita clan and later, the Nasu clan.  Accompanying this transition, Sukekuni acquired the name of the Morita clan.  Sukekuni was a mainstay of the family supporting Suketane.  In 1560, Sukekuni was recognized by Suketane for his contributions at the Battle of Odakura.  In 1563, when Ōzeki Takamasu, Fukuhara Suketaka, and others incited followers of the Upper Nasu family to defect to Satake Yoshishige, he did not respond to their appeals and continued to support Suketane.

Sukekuni died in 1566.  Morita Sukenobu is deemed to have been his son and inherited the headship of the Morita clan.  In 1590, members of the Nasu clan were late in deploying for the Conquest of Odawara led by Toyotomi Hideyoshi.  As a result, the Nasu clan was removed from its position as well as the Morita clan for being complicit with the Nasu.