Head of the Sagami Miura clan, known by his religious name Dosun. His birth year is given as either 1451 or 1453. In 1512 he lost Okazaki Castle to the invading Hojo Soun (Ise Moritoki), retreating first to Sumiyoshi Castle and then, the following year, to Arai Castle. After a three-year siege, Arai Castle fell on July 11, 1516, and he died alongside his son Yoshioki and their retainers, ending the Sagami Miura line. The bay, said to have run red with the blood of the fallen, gave the area its name "Aburatsubo" (Oil Jar).

Known for the tenacity that sustained a three-year siege. His son Yoshioki is depicted in the "Hojo Godaiki" as a warrior of legendary strength; father and son are remembered together for their valor.

The Battle of Arai Castle sealed the Later Hojo conquest of Sagami Province, ending the ancient Miura clan lineage that traced back to the Kamakura period. The site remains a historic and tourist landmark in Miura City today.