What is "sarushima"

, is a small island located off Yokosuka, Kanagawa in Japan. It is the only natural island in Tokyo Bay. Sarushima was used as a battery by the Tokugawa shogunate during the Edo period, and after the Meiji Restoration in 1868, the island was developed as the Yokosuka Navy Yard.

Matthew C. Perry named the island Perry Island in 1853.