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Kasai-Osaki Uprising
Conflict: Kasai-Osaki Rebellion
Date: 1591
Place: Miyagi Province, Oshu region, northern Japan
Outcome: Toyotomi victory

Toyotomi Toyotomi Shogunate

Rebels Peasant Army


Concubine Kai
Hideie Ukita
Ujinaga Narita
Yoshitsugu Otani

Harunobu Kasai
Yoshitaka Osaki
Magoichi Saika






near total

The Kasai-Osaki Uprising was a peasant rebellion in 1591 by Date retainers loyal to Masamune Date, who fought against the Toyotomi, who took away their lands. The rebellion did well at first, but Concubine Kai crushed it.


When Hideyoshi Toyotomi unified Japan in 1590, he became a dictator who ruled all of the islands from Kyoto as Shogun, Kampaku, and Sessho. Masamune Date, who had served as a general of Hideyoshi at the Fall of Odawara, was stripped of his lands and his possessions, causing the people of Miyagi province and Date clan retainers to form the Peasant Army in a rebellion. Masamune did not order the rebellion nor did he support it, and the two leaders of the rebellion were Harunobu Kasai and Yoshitaka Osaki. The "Kasai-Osaki Uprising" of 1591 was one of the last acts of rebellion against the Toyotomi Shogunate.


Shogun Hideyoshi sent Concubine Kai to put down the uprising. The rebels fought with vigor and were able to surround Ujinaga Narita's unit, and the Peasant Army very nearly eliminated him, had it not been for Concubine Kai relieving him, her father. Eventually, the Toyotomi army began to falter and Hideyoshi sent Yukimura Sanada with additional Shogunate troops. Reinforcements came for the rebels as well, led by the Saika renegades leader Magoichi Saika. The Saika Riflemen proved to be fierce opponents, and they did some damage on the Toyotomi Army before Toyotomi ninja Kunoichi stopped them by wounding Magoichi. With their riflemen gone, the Peasant Army was again a mob of spearmen and bowmen. After a good fight, the rebels were finally defeated. Harunobu Kasai and Yoshitaka Osaki were both killed in the battle, along with most of the Date retainers.


Kanbei Kuroda prosecuted Masamune Date, believing that he had been responsible for sending the rebels rifles and other supplies. Using a letter as evidence, Kanbei showed the commands to Masamune. Masamune pointed out to Hideyoshi Hashiba that the seal was wrong, and Hideyoshi forgave Masamune for his instigation of the rebellion, and he went on to fight in the Korean campaign.