Iemasa Hachisuka was born in Awa Province, Shikoku, in the castle town of Tokushima to Masakatsu Hachisuka. In 1582, after serving the Oda clan, he fought under the command of Hideyoshi Hashiba in his campaigns such as Yamazaki, Komaki-Nagakute, Kyushu, and Odawara Castle. In 1598, when Hideyoshi died, he sided with Masanori Fukushima's Fukushima clan, and fought against the Ishida clan in the Siege of Kyoto. Iemasa was defeated, and switched his allegiance to the Tokugawa, and fought at the Battle of Sekigahara alongside Ieyasu Tokugawa. After this, he ruled over Awa Province until his death in 1639 at the age of 81.