Arai Castle

Arai Castle was a hill castle on a headland jutting into Aburatsubo Bay on the Miura Peninsula. Its name was also written 荒井城, and it was also called Koajiro Castle and Misaki Castle. It is remembered as the place where Miura Dōsun (Yoshiatsu) and his clan, attacked by Ise Moritoki (Hōjō Sōun) of Odawara, fell after a long siege in the early Sengoku period.

Founding and the Miura clan

The builder is given as the Miura clan, but the year of construction is unknown. In 1494 (Meiō 3) Miura Yoshiatsu (Dōsun) is said to have seized the castle from Miura Tokitaka and his son Takanori.

The war with Hōjō Sōun

In 1512 (Eishō 9) the Miura lost Okazaki Castle to Ise Moritoki (Hōjō Sōun), and after holding Sumiyoshi Castle they withdrew to Arai Castle the following year. The siege lasted about three years, and Arai Castle fell in 1516 (Eishō 13). Yoshiatsu died with his son Yoshioki, and the Sagami Miura clan was destroyed; it is counted as the second destruction of the Miura clan.

Structure and excavation

It was a hill castle on a 26 m promontory, with earthen ramparts, enclosures, and dry-moat cuts listed as remains. The presumed main enclosure lies near the grounds of the University of Tokyo's Misaki Marine Biological Station. A 1992 excavation found postholes of buildings, a dry moat, and 16th-century ceramics. A pit also yielded a large quantity of human bones, which has been reported as possibly a feature where war dead were discarded.

The name Aburatsubo

One account says the name "Aburatsubo" (oil jar) comes from the blood of the Miura clan floating on the sea like oil. This is a local tradition, not an established fact.

Abandonment and today

The castle is said to have been abandoned around 1590 (Tenshō 18), possibly after Toyotomi Hideyoshi's Odawara campaign, but this is not settled. Most of the site is now within the grounds of the marine station. A memorial tower for Miura Yoshiatsu stands beside the path down to Dōami Beach on the north side of the campground, and visitors may stroll there freely.