“Sunpu Castle (Sunpu-jō) is a Japanese castle in Shizuoka City, Shizuoka Prefecture. The nickname of this feudal fortress was the ‘Castle of the Floating Isle’. It was also referred to as Fuchu Castle or Shizuoka Castle. During the Muromachi period, the Imagawa clan ruled Suruga Province from their base at Sunpu (modern-day Shizuoka City). It is not certain exactly when a castle was built on this site.”