After the Takeda family succumbed, Kai Province became the fiefdom of Oda Nobunaga. When Oda died it came under the governance of Tokugawa Ieyasu. When Toyotomi Hideyoshi unified the country, he ordered the castle's construction. It was begun in 1583 and later completed by Toyotomi's brother-in-law, Asano Nagamasa, and his son. After the Battle of Sekigahara, Kōfu Castle fell into the hands of the Tokugawa family to whom it belonged until the end of the Tokugawa shogunate.