Born in 1168, eldest son of Miura Yoshizumi, he inherited leadership of the powerful Miura clan of the Miura Peninsula. A childhood contemporary and ally of Hojo Yoshitoki, he was simultaneously a cunning schemer who always sought to maximize his clan's advantage near the centers of power. In the Wada War (1213), he detected Wada Yoshimori's rebellion in advance yet switched sides to the Hojo at the decisive moment, ensuring the Wada's annihilation. In Sanetomo's assassination (1219), he was suspected of sheltering or manipulating the killer Kugyo—his true role remains debated. He fought on the shogunate's side in the Jokyu War (1221), gaining further rewards. These political victories made the Miura one of the mightiest clans in the shogunate. Yet his legacy of power bred conflict with the Hojo tokuso line, culminating in the destruction of the Miura in the Hoji War (1247) under his son Yasumura. He died in 1239 at age 72.