시모쓰케 국
After Tokugawa Ieyasu took control over the Kantō region in 1590, he assigned a 13,000 "koku" holding in northern Shimotsuke Province to Ōzeki Takamasu, the head of one of the seven leading samurai clans from the area. His son, Ōzeki Sukemasu, fought a rear-guard action against the Uesugi clan in Aizu during the Battle of Sekigahara and was rewarded with an increase in "kokudaka" to 20,000 "koku" and was confirmed as "daimyō" of Kurobane.