Oka Castle@しずくいし Okajo is a mountain castle built during the Warring States period in Taketa City, Oita Prefecture. The castle is located on Mount Okayama at an altitude of about 400 meters, surrounded by steep slopes and valleys. It was mainly used by powerful feudal lords such as the Otomo clan and the Shimazu clan, and is known as a valuable historical site that recalls the Warring States period. Today, it has been developed into Okajo Site Park, where the castle ruins, stone walls, and earthen walls are preserved, providing visitors with the opportunity to enjoy both history and nature. [Text: @AI, Translation: @AI]