Kinojo Castle (鬼ノ城) is located in Soja City, Okayama Prefecture. The name literally means "Demon Castle" or "Castle of a Demon." However, no clear historical records of the castle exist, and it was only discovered in 1971.

It's now believed to be the oldest castle in Japan, possibly one of a dozen Korean-style mountain fortifications built in Western Japan in the seventh century, which are mentioned in the eighth-century Nihon Shoki, or Chronicles of Japan, the second-oldest book of classical Japanese history.

The castle is also believed to be connected to the story of Kibitsuhiko-no-mikoto, a legendary Japanese prince who defeated Prince Ura of Kudara (also known as Baekje, a large kingdom that comprised most of western Korea), who supposedly lived in a castle known as the Castle of a Demon—a.k.a., Kinojo. This story in turn became the basis of the folktale of Momotaro, the Peach Boy, who assembled various animal friends to fight against a demon in a distant land.

Find out more about this mysterious castle at Zooming Japan below!