O-Ie Sōdō
Tsugaru Yasuchika was the eldest son of Tsugaru Akitaka, the 5th lord of Kuroishi, a 4000-"koku" "hatamoto" holding created for the second son of Tsugaru Nobuhira, the 2nd "daimyō" of Hirosaki. Nobuhira was married to a daughter of Ishida Mitsunari; however, for political reasons after the establishment of the Tokugawa shogunate, he found it expedient to reduce her to concubine status and to marry an adopted daughter of Tokugawa Ieyasu instead. Nevertheless, the son of his first wife, Tsugaru Nobuyoshi remained his heir, which resulted in an "O-Ie Sōdō" by supporters of the son by his second wife, Tsugaru Nobufusa. The shogunate ruled in favour of Nobuyoshi, and the Kuroishi holding was created for Nobufusa and his descendants.