In 1512, as the capstone of his pacification of Sagami, Hojo Soun built Tamanawa Castle as a forward base for attacking the Miura clan on the Miura Peninsula. Commanding the northwest of Kamakura, the 'impregnable' castle became a linchpin of Later Hojo control of southern Sagami. Soun installed his second son Ujitoki as first lord, and the Tamanawa Hojo — including the fierce Hojo Tsunashige — held it for generations.

During the 1590 Odawara Campaign, the Tamanawa lord Hojo Ujikatsu held the formidable castle with some 700 cavalry, but surrendered bloodlessly in the fourth month after the mediation of the monk Joko of Ryuhoji and Tokugawa Ieyasu's call to capitulate. Ieyasu's persuasion opened one Hojo branch castle after another without bloodshed, hastening the pacification of the Kanto; Ujikatsu went on to serve the Tokugawa.

During Toyotomi Hideyoshi's 1590 Siege of Odawara against the Later Hojo clan, Tamanawa Castle lived up to its "impregnable" reputation, holding out for a long time. Its lord, Hojo Ujikatsu, eventually surrendered peacefully after persuasion by Tokugawa Ieyasu and mediation by a monk of Ryuhoji Temple, making it one of the last Hojo strongholds standing until the clan's fall.