The Mizoguchi were originally from Owari Province and were a cadet branch of the Takeda clan. Mizoguchi Hidekatsu was a retainer of Niwa Nagahide. His abilities cam to the attention of Niwa's overlord, Oda Nobunaga, who granted him a 5000 "koku" fief in what is now Takahama, Fukui. Following Nobunaga's assassination, he entered the service of Toyotomi Hideyoshi and was active at the Battle of Shizugatake against Shibata Katsuie, for which he was granted a 44,000 "koku" estate in Kaga Province. In 1586, he was recognized by Hideyoshi as an independent "daimyō" and was even authorized to use the "Toyotomi" surname. During the Japanese invasions of Korea (1592–1598), he remained in Japan as part of the guard of Nagoya Castle. In 1598, he was transferred to Shibata and his "kokudaka" was increased to 60,000 "koku". Following the Battle of Sekigahara, he was confirmed in his holdings by the Tokugawa shogunate.