Hara Tanekiyo served as a bushō during the Sengoku period.  He was a retainer of the Chiba clan and served as the lord of Oyumi Castle in Shimōsa Province.

Tanekiyo was born as the lineal heir to Hara Tanetaka, a bushō and the head of the Oyumi-Hara family. 

Although Tanekiyo was the heir to the main branch of the Shimōsa-Genji, at the time he was born, Tanetaka appears to have adopted his younger brother, Hara Tomotane, and transferred headship of the clan to him.  As a result, Tanekiyo may initially have been tendered for adoption by a family member.  In 1518, after Ashikaga Yoshiaki toppled Oyumi Castle, Hara Mototane (the heir of Tomotane) serving as lord of the castle was killed in action, ending the lineage of Tomotane.  Tanekiyo became his successor, but pressure from Yoshiaki caused him to flee to the base of Takagi Taneyoshi at Negiuchi Castle (or Kogane Castle), and then turn for support to Hōjō Ujitsuna.

In 1538, at the First Battle of Kōnodai, Yoshiaki was killed.  With the backing of Ujitsuna, Tanekiyo reclaimed Oyumi Castle.  Thereafter, he renovated the site and changed the characters in the name of Oyumi Castle.  He then served as a key figure with respect to the policies of the Chiba toward the Gohōjō, wielding the real authority in the Chiba clan over three generations – Chiba Masatane, Chiba Toshitane, and Chiba Chikatane.  In particular, Chikatane was frustrated by the autocratic behavior of Tanekiyo and his son, Hara Tanesada.  Chikatane stood in opposition to the Gohōjō clan and joined forces with Ashikaga Haruuji, the Koga kubō, who shared his opposition.

The Chiba-Myōken Shrine was rebuilt under the guidance of Tanekiyo, demonstrating his influence inside and outside of the clan.