Ōsaki

The Ōsaki were daimyō of Mutsu's five Ōsaki districts, descended from the Shiba and Seiwa Genji. Their founder Shiba Iekane was sent north as Ōshū kanrei; from the fifth head Mitsuaki, the family took its name from its lands along the Eai and Naruse rivers.

In early Muromachi times they held authority over Mutsu and Dewa, but rival governors and Southern Court resistance confined their rule to the Ōsaki country. In 1400 the head Akimochi was killed after his plot against the Kamakura government was exposed.

In the Sengoku age Yoshinao put down a vassal revolt with Date Tanemune's aid and became a Date dependent. His son Yoshitaka defeated Date Masamune in 1588 but submitted after the Ashina fell in 1589. Yoshitaka's lands were confiscated in 1590, and a rising of old retainers could not restore the house.