Iwabitsu Castle, located in Agatsuma County, Gunma Prefecture, is a mountain castle that was captured by the Sanada clan as vassals of the Takeda clan. It was also the base of Sanada Masayuki's base before he built Ueda Castle, and it is said that in the event of the Takeda clan's downfall, he planned to invite his lord, Katsuyori, to this castle for a decisive battle with the Oda-Tokugawa forces. Even after the Takeda clan's downfall, Iwabitsu Castle remained important as an intermediate base for the Sanada domain, and it is said that the prosperity of the castle town known as Hirakawado reached the ears of Tokugawa Ieyasu in Edo. Both the castle and the town were abandoned due to the One Castle per Province Order. Currently, a hiking trail and a tour route to the castle ruins have been developed.