The Kasai of Mutsu province were locally powerful and clashed with the Hatakeyama clan in the Kurihara area. They later allied with the Date but suffered internal disturbances (such as the Temmon no ran of 1547) and were later invaded by their erstwhile allies and badly defeated at Tasuku. After this defeat a number of retainers began to drift away and the power of the family waned as it accepted Date control. They were dispossessed in 1590 by Toyotomi Hideyoshi for tardiness in attending the Seige of Odawara. Former Kasai retainers and farmers rioted in 1591 against Kimura Hidetoshi and his son Shigemasa (whom Toyotomi Hideyoshi had placed in control of the Kasai lands) and had to be suppressed by Date Masamune.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005