The Ikoma clan was originally a powerful 171,800-koku daimyō clan ruling Takamatsu Domain in Sanuki Province. However, the Ikoma were dispossessed in 1640 due to gross mismanagement by Ikoma Takatoshi which resulted in an O-Ie Sōdō by his retainers. The Tokugawa shogunate reassigned the clan to the newly created 10,000 koku Yashima Domain in the inhospitable foothills of Mount Chōkai in central Dewa Province, where Ikoma Takatoshi was ordered to remain under house arrest for over 20 years. Furthermore, in 1659 his son and heir Ikoma Takakiyo was forced to divide 2000 koku of his inheritance to a younger brother, and thus the clan lost its status as a daimyō clan, and was reduced to the ranks of the hatamoto.