Like Medieval Europe, Japan also developed castles and forts, though they are very different. Japanese castles do have exotic features. They look similar to temples and palaces found in Japan and China. Most of them are built on hills. They are mainly used for defense. During the chaotic Warring States period and other periods with civil strife, castles protected millions of people. One famous example is the Azuchi Castle, which belongs to Oda Nobunaga.
Kumamoto Castle. gaijinpot.scdn3.secure.raxcdn.com/app/uploads/sites/6/2018/07/kumamoto-castle-main.jpg.
"Japanese Castle." Wikipedia, Wikimedia Foundation, 19 Mar. 2021, en.wikipedia.org/wiki/Japanese_castle.