Born as a son of Hara Tanetaka, senior retainer of the Chiba clan. In 1518 he inherited the headship of a collateral branch of the Hara family. After Ashikaga Yoshiaki, the self-proclaimed Oyumi Kubo, was killed at the First Battle of Konodai in 1538, he recovered his family's territory with Hojo Ujitsuna's backing and rebuilt his base as Oyumi Castle. He went on to dominate Chiba clan politics as the architect of its pro-Hojo policy through three generations of lords, dying in 1556.

A pragmatic realist who pursued alliance with the Later Hojo to ensure the survival of his lord's Chiba clan. His grip on real power across three generations of lords reveals considerable political skill.

The Hara clan's rule from Oyumi Castle laid the regional foundation that would later become the Edo-period Oyumi Domain under the Morikawa clan.