Okayama Castle’s main keep is available for rental from 5:30 PM – 9:30 PM. Why not spend a special time in a unique setting at Okayama Castle for parties or social gatherings? In conjunction with the nighttime use of the main keep, it is also possible to host a party in the plaza in front of the keep, with the illuminated castle as the backdrop.
https://okayama-castle.jp/gather-utilization/