A vassal based in Doi, Sagami Province (present-day Yugawara, Kanagawa). An established local strongman, he was one of the first to join Yoritomo's uprising in 1180. He is best remembered for guiding the retreating Yoritomo to the mountains near Manazuru after the disastrous defeat at Ishibashiyama and hiding him inside a hollow tree to evade Taira pursuers—an act of desperate loyalty that earned Yoritomo's lasting gratitude. He accompanied Yoritomo to Awa and continued serving throughout the campaigns to pacify Kanto and pursue the Taira. At Ichi-no-Tani (1184) he joined the flanking force that attacked the Taira stronghold. He was appointed guardian of Aki and Suo provinces after the Taira's defeat. He reportedly died around 1191. His son Tohira became the ancestor of the Kobayakawa clan, whose lineage continued into the Sengoku era.

A warrior of unwavering loyalty. He risked his life to protect Yoritomo after Ishibashiyama. Regarded as a model of the faithful old-style samurai who served without seeking glory.

The story of saving Yoritomo at Ishibashiyama is one of the most dramatic episodes of the shogunate's founding. Historical sites related to the Doi clan remain in Yugawara.