Tanaka Castle, or popularly called “Kame-jo (Turtle Castle),” was located in Fujieda City, Shizuoka Pref. The castle was originally called Tokunoisshiki Castle, but it was captured by Takeda Shingen in 1570. Shingen ordered his retainer, Baba Mino-no-Kami, to build an extension and renamed it Tanaka Castle. In the battle with Tokugawa Ieyasu in 1582, when the castellan of nearby Ejiri Castle, who had sided with the Takeda clan, defected to the enemy, Tanaka Castle was completely detached and the castellan, Yoda Nobushige, was obliged to take the advice of peace settlement by the Tokugawa forces and surrendered the castle. Later in 1601, the outmost compound was added by the new castellan, Tadatoshi Sakai, and the castle had been resided by the successive domain lords until it was dismantled with the Meiji restoration in 1868. The castle compounds were built in a concentric circle, which is very unique in the nation. At the present time, Nishimashizu Elementary School stands on the site of Honmaru (the main Castle) and Ninomaru (the second castle) and Nishimashizu Junior High School on Sannomaru (the third castle).