Ichigoyama Castle is located at the eastern peak of Mt. Ushibuse (491 m) in Yoshii-cho, Gunma Pref. It is said that the castle was built in the late Muromachi period (1336-1573) as an attached castle of Hirai Castle, which was resided by the Uesugi clan. Located at the top of such a high peak, the castle is thought to have been used as a base to send smoke signals during the Warring States period (1493-1573). The castle fell in 1563 by the attack of Takeda Shingen. It is presumed that several outer compounds separated by dry moats were constructed but there are almost no ruins remaining now. The area was arranged into Ushibuseyama Natural Park to provide citizens with recreation and relaxation. On the castle ruin stands a three-story mock donjon with a commercial museum of Yoshii-cho on the 1st floor, a historical museum on the 2nd floor, and an observatory on the 3rd floor, from which visitors can command a 360°panoramic view.