Yokota Tsunamura served as a bushi during the Sengoku period.

The Yokota were among prominent members of the Utsunomiya clan of Shimotsuke Province, on a par with the Ujiie, the Shionoya, and the Takō families.

Etchū-no-kami Yorinari, the second son of Utsunomiya Yoritsuna who was a fifth generation head of the Utsunomiya branch of the Fujiwara-Hokke from the mid-Kamakura period, settled in the Yokota township and adopted Yokota as his surname.  Many illegitimate families descended from the Yokota, including the Kaminokawa, the Nakamikawa, the Imaizumi, the Takebayashi, the Matsuno, the Ishii, the Osakabe, and the Kuwajima.

Tsunamura was  born as the son of Yokota Tsunahide and became the head of the Yokota house in the Kawachi District of Shimotsuke.

Tsunamaru had six sons.  On 9/17 of Tenbun 18 (1549), five of his sons fought and died in the Battle of Kitsuregawa-Sōtomezaka.  This conflict was waged between the Nasu clan led by Nasu Takasuke and the Utsunomiya clan led by Utsunomiya Hisatsuna.  These are known as the Five Brothers of the Yokota.

Thereafter, the Yokota clan was inherited by Yokota Tsunahisa, the youngest and only surviving son of Tsunamaru.