Asonuma

The Asonuma were a branch of the Fujiwara-descended Ashikaga house of Shimotsuke Province, founded by Hirotsuna, who took his name from the Asonuma estate. During the Genpei War they followed Minamoto no Yoritomo, and Hirotsuna became a Kamakura gokenin.

His service in the Oshu campaign of 1189 won him the stewardship of the Tono estate in Mutsu, inherited by his younger son Chikatsuna, who built Yokota Castle. The Shimotsuke main line eventually became retainers of the Sano clan. In 1334 the Tono head Tomotsuna had his holdings confirmed by the Southern Court general Kitabatake Akiie.

In 1590 the Tono head Hirosato was reduced to vassal status under the Nanbu for failing to appear at Toyotomi Hideyoshi's Odawara campaign. In 1600 kinsmen revolted while his heir Hironaga was away and drove him out, extinguishing the Tono main line; a branch in Aki Province lived on as retainers.