Shiroishi Castle, or known as Masuoka Castle, was once located in the center of Shiroishi City, Miyagi Pref. This flatland mountain castle stood on top of the hill with an altitude of 76 m. Honmaru (the main castle), Ninomaru (the second castle), Naka-no-maru (inner castle) and Nishi-kuruwa (western outer compound) were built on the top, while Numa-no-maru, Minami-no-maru (southern compound), Tatsumi-kuruwa (south-east outer compound), Obi-kuruwa, Umaya-kuruwa (stable) were build on the hill side. The Tatebori River flew around the hill and the southern side was blocked with Kara-bori (dry moat). On the flat land across the river stood San-no-maru (the third castle) and Soto-kuruwa (outer compound). The castle was mainly used as a branch castle of Date clan, who ruled Sendai Province. Several generations of the chief retainers, Katakura family, resided in this castle. As this castle was not counted as the subjects of dismantlement as per the Ikkoku-ichijo (One Castle Per Province) order established by the Tokugawa Shogunate, it remained until the Meiji Restoration. The part of Honmaru including the donjon was rebuilt of wood in 1995. At the present time, the area around the castle is arranged as a park. The castle reminds us of a long history of battles that broke out from the Heian period to the end of Tokugawa Shogunate.