Gion Castle was resided by the Oyama clan, which gained prosperity in the area around present-day Oyama City, Tochigi Pref. from the time of Genpei War (1180-1185) through the end of the Warring States period (the late 16th century). The time of its construction is unknown, but it is referred to in the historical record written in the 14th century. The name “Gion” is said to have been derived from the name of the shrine, Gion-sha (present-day Suga Shrine), which was worshipped as the guard of the castle. The Oyama clan moved to this castle in the early Warring States period (the 15th century). The castle was an important base for the clan to fight battles in the Kanto region. Assigned as the governor of Shimotsuke province (present-day Tochigi Pref.), the Oyama clan wielded power in this region; however the clan was involved in the conflict with the Hojo clan and was finally destroyed by the Hojo clan in the Warring States period. In 1619, when Honda Masazumi, the castellan at the time, was promoted to the domain lord of Utsunomiya province, Gion Castle was dismantled. At the present time, the castle ruin is improved into a park and provides citizens with the place of recreation and relaxation. It is also known as a cherry blossom viewing spot.