The "Ninonomaru" existed until the Kaei period (1848–54). Facilities for conducting clan affairs, residences for retainers, gardens, and stables ("Mukaiyashiki") were located there. The western two-thirds of the area was known as the "Oshiro" (the castle), while the eastern one-third was called "Ninomaru Goten" (the palace). The gardens originally included flowering trees, stone lanterns, and a traditional Japanese-style tea arbour. After the Meiji Restoration, the original was demolished to build army barracks, but it was restored and designated as an official scenic spot after the war.